The USC Adult Twin Cohorts: International Twin Study and California Twin Program.

Science.gov (United States)

Cozen, Wendy; Hwang, Amie E; Cockburn, Myles G; Hamilton, Ann S; Zadnick, John; Mack, Thomas M

2013-02-01

The study of twin subjects permits the documentation of crude heritability and may promote the identification of specific causal alleles. We believe that at the current time, the chief research advantage of twins as subjects, especially monozygotic twins, is that the commonality of their genetic and cultural identity simplifies the interpretation of biological associations. In order to study genetic and environmental determinants of cancer and chronic diseases, we developed two twin registries, maintained at the University of Southern California: The International Twin Study (ITS) and the California Twin Program (CTP). The ITS is a volunteer registry of twins with cancer and chronic disease consisting of 17,245 twin pairs affected by cancer and chronic disease, respectively, ascertained by advertising in periodicals from 1980-1991. The CTP is a population-based registry of California-born twin pairs ascertained by linking the California birth records to the State Department of Motor Vehicles. Over 51,000 individual California twins representing 36,965 pairs completed and returned 16-page questionnaires. Cancer diagnoses in the California twins are updated by regular linkage to the California Cancer Registry. Over 5,000 cancer patients are represented in the CTP. Twins from both registries have participated extensively in studies of breast cancer, melanoma, lymphoma, multiple sclerosis, systemic lupus erythematosus, diabetes mellitus type 1, mammographic density, smoking, and other traits and conditions.

Perinatal hepatic infarction in twin-twin transfusion.

LENUS (Irish Health Repository)

O'Sullivan, M J

2012-02-03

We report a case of a twin pregnancy which was complicated by a twin-twin transfusion in which the recipient twin was noted to have an intra-abdominal echogenic mass. This twin died at two days of age of hepatic infarction. The donor twin was healthy at birth, at thirty weeks\\' gestation, and did not have any subsequent problems. Fetal intra-abdominal echogenicity may be a marker of hepatic infarction.

'Twin2twin' an innovative method of empowering midwives to strengthen their professional midwifery organisations.

Science.gov (United States)

Cadée, Franka; Perdok, Hilde; Sam, Betty; de Geus, Myrte; Kweekel, Liselotte

2013-10-01

midwives need professional support from a national midwifery organisation to be able to provide the services that are by regulatory mechanisms and accreditation expected of them. Not all midwives in the world are united in a professional organisation. The aim of this project was to strengthen the midwifery organisations of Sierra Leone and the Netherlands. During the process of the project it was realised that the development of a platform of exchange at organisational level would be enhanced by introducing personal exchange between individual midwives. In response to this new insight the original project plan was adjusted by incorporating the twin2twin method. twin2twin is a feminist methodology of mutual exchange between twenty pairs of midwives from different organisations (in this case Sierra Leone and the Netherlands). The method can be distinguished by 10 specific steps. It was developed, used and (re)evaluated through focus group discussions, storytelling and written evaluations. twinning of organisations was strengthened by adding a human component to the process. With the use of the 'twin2twin' method, midwives were encouraged to invested in a professional and personal bond with their 'twin sister'. This bond was independent and went beyond the relatively short four year project period. Through personal engagement and mutual exchange of knowledge and skills, midwives empowered each other to build and strengthen their midwifery organisations both in Sierra Leone and the Netherlands. (Empowerment refers to the expansion in people's ability to make strategic life choices in a context where this ability was previously denied to them (Narayan, 2005); organisational empowerment includes processes and structures that enhance members' skills and provides them with the mutual support necessary to effect community level change (Zimmerman, 1995).). despite challenges we are convinced that twin2twin can be of additional benefit for the success of other projects

A proof of the conjecture on the twin primes

Energy Technology Data Exchange (ETDEWEB)

Zuo-ling, Zhou [Department of Lingnan college, Sun Yat-sen University GuangZhou, GuangDong, 510275 (China)

2016-06-08

In this short note, we have proved the conjecture on twin primes using some thoughts of the set theory. Firstly, using the original sieve method and a new notation(concept)introduced by myself, the conjecture on twin primes is summed up as an elementary successive limit, afterwards we form a subsequence of positive integers,and using it,we prove that the successive limits are commutative and complete the proof of the conjecture on twin primes We also give a more straightforward proof of the conjecture.

Calcite Twin Analysis in the Central Andes of Northern Argentina and Southern Bolivia

Science.gov (United States)

Hardesty, E.; Hindle, D.

2005-12-01

The use of calcite twinning to infer compression directions and strain axes patterns has been applied widely in both fold and thrust belts, and continental interiors. Calcite twinning is noted to be one of the most precise methods for determining the internal strain of deformed rocks. Until now, such data from the deformed plate boundary of the Central Andes were lacking. This study has examined twinning orientations along the deformed Andean foreland (southern Bolivia and northern Argentina) from -25 to -20 latitude. In the Central Andes, we find an abundance of calcite twins in intervals of the Cretaceous age Yacorite limestone. Twin samples were collected, measured for orientation and type (I and II can be best used for strain analysis), and processed using the Groshong method, to give resultant strain tensors. The orientations of the twin short axes trend mostly NE-SW, which is close to the plate convergence direction. However, in a limited number of samples from the north, adjacent to the southern culmination of the active Subandean fold thrust belt, they trend NW-SE. This difference may be related to the more active, or more recent, shortening of the southern portion of the Eastern Cordillera, south of the culmination of the Subandean belt. This implies that twin short axes vary consistently with respect to geographic location and local tectonic regime. NW-SE trends in the northern region match well with fault kinematic studies in rocks pre-dating the San Juan del Oro unconformity (9-10 Ma). NE-SW trends in the south could correspond to much younger (~1-3 Ma) fault kinematic trends. In the Eastern Cordillera, where there is present day tectonic activity, the plunges of the twin short axes are found to be almost horizontal. This suggests that the twins were formed after folding occurred.

Neurodevelopmental outcome at 2 years in twin-twin transfusion syndrome survivors randomized for the Solomon trial.

Science.gov (United States)

van Klink, Jeanine M M; Slaghekke, Femke; Balestriero, Marina A; Scelsa, Barbara; Introvini, Paola; Rustico, Mariangela; Faiola, Stefano; Rijken, Monique; Koopman, Hendrik M; Middeldorp, Johanna M; Oepkes, Dick; Lopriore, Enrico

2016-01-01

-up evaluation was detected in 12 of 107 cases (11%) in the Solomon and in 10 of 109 cases (9%) in the standard group (P = .61). Neurodevelopmental impairment was due to cerebral palsy in 1 case (1%; spastic unilateral) in the Solomon group and in 2 cases (2%; spastic unilateral and spastic bilateral) in the standard group (P = .58). Cognitive development neurodevelopmental impairment between the Solomon and standard laser techniques. In view of the reduction of short-term complications and the absence of increased adverse long-term effects, these data support the use of the Solomon technique in the treatment of twin-twin transfusion syndrome. Copyright © 2016 Elsevier Inc. All rights reserved.

Global inter-annual gravity changes from GRACE: Early results

DEFF Research Database (Denmark)

Andersen, Ole Baltazar; Hinderer, J.

2005-01-01

with an accuracy of 0.4 muGal corresponding to 9 mm water thickness on spatial scales longer than 1300 km. Four of the most widely used global hydrological models have been investigated for their spatial comparison with GRACE observations of inter-annual gravity field variations due to changes in continental water...... storage. The Global Land Data Assimilation System model has a spatial correlation coefficient with GRACE observations of 0.65 over the northern hemisphere. This demonstrates that the observed gravity field changes on these scales are largely related to changes in continental water storage.......Fifteen monthly gravity field solutions from the GRACE twin satellites launched more than two years ago have been studied to estimate gravity field changes between 2002 and 2003. The results demonstrate that GRACE is capable of capturing the changes in ground water on inter-annual scales...

Prenatal x-ray and childhood cancer in twins

International Nuclear Information System (INIS)

Harvey, E.B.

1983-01-01

In order to evaluate the causal nature of the relationship between prenatal x-ray exposure and childhood cancer, a case control study was conducted in a population of over 32,000 twins born in the state of Connecticut from 1930-1969 and followed to age 15. Thirty-two incident cancer cases were identified by linking the Connecticut Twin and Tumor registries. Each case was matched with four controls on year of birth, sex, race, and survival. Prenatal x-ray information as well as reproductive, delivery and birth data were obtained from the hospital of birth, the physician providing prenatal care, private radiology groups and interviews with hospital staff. The case control study which obtained exposure information on selected subjects found an increased risk of childhood cancer from prenatal x-ray exposure. The risk associated with radiation exposure was elevated in the following subcategories: mother with history of pregnancy loss, a gravity greater than 1, under 30 years of age, and twins weighing five pounds or more at birth. The results, though based on small numbers, strengthen the association between prenatal x-ray exposure and childhood cancer

'Biracial'-Looking Twins: A New Twin Type?/Twin Research: Twins with Cystic Teratomas; Sleep Quality and Body Mass Index; Previable Membrane Rupture/Print and Online Reports: Twins Born to a Sister Surrogate; NASA Twin Study; African-Cosmopolitan Twin Fashion Inspirations; Triplet Hockey Stars.

Science.gov (United States)

Segal, Nancy L

2017-06-01

Dizygotic (DZ) co-twins born to mothers and fathers from different racial or ethnic backgrounds often resemble one parent much more than the other. As such, these pairs comprise a unique subset of twins for investigating how others' responses to their different looks may affect their personalities and self-esteem. This article describes some of these twin pairs and some challenges of raising them, and suggests ways they may be used in research. Next, recent twin research on cystic teratomas, relations between sleep quality and body mass index, and previable membrane rupture is described. The final section concerns twins, twin studies, and related events in the media, namely: twins born to a sister surrogate, the NASA twin investigation, inspiring African-Cosmopolitan twins in fashion, and triplet Hockey Stars.

[Adult twins].

Science.gov (United States)

Charlemaine, Christiane

2006-12-31

This paper explores the deep roots of closeness that twins share in their youngest age and their effect on their destiny at the adult age. Psychologists believe the bond between twins begins in utero and develops throughout the twins' lives. The four patterns of twinship described show that the twin bond is determined by the quality of parenting that twins receive in their infancy and early childhood. Common problems of adult twins bring about difficulties to adapt in a non-twin world. The nature versus nurture controversy has taken on new life focusing on inter-twin differences and the importance of parent-child interaction as fundamental to the growth and development of personality.

The Fourth International Network of Twin Registries: Overview from Osaka/Research Reviews: Familial Fraternal Twinning; Twin Study of Masculine Faces; Physical Aggression and Epigenetics; Prenatal Education for Parents of Twins/Current Events: 2016 Guinness Book of World Records; Oldest Living Male Twins; Twins Reunited at Sixty-Nine; Panda Twins; Twins.com.

Science.gov (United States)

Segal, Nancy L

2015-12-01

The 4th International Network of Twin Registries (INTR) Consortium Meeting took place in Osaka, Japan, September 28-29, 2015. The venue was the Osaka Medical Center for Medical Innovation and Translational Research. An overview of presentations and other activities is provided. Next, 1930s research on familial fraternal twinning, preference for masculine faces, physical aggression and epigenetics, and a prenatal education program for parents of multiples are described. Current twin-related events include the 2016 Guinness Book of World Records (GWR), the oldest living male twins, newly reunited twins, the birth of panda twins and a controversial twin-based website.

The Placenta in Twin-to-Twin Transfusion Syndrome and Twin Anemia Polycythemia Sequence.

Science.gov (United States)

Couck, Isabel; Lewi, Liesbeth

2016-06-01

Twin-to-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS) are complications unique to monochorionic twin pregnancies and their shared circulation. Both are the result of the transfusion imbalance in the intertwin circulation. TTTS is characterized by an amniotic fluid discordance, whereas in TAPS, there is a severe discordance in hemoglobin levels. The article gives an overview of the typical features of TTTS and TAPS placentas.

Airborne gravity survey of Lincoln Sea and Wandel Sea, north Greenland

DEFF Research Database (Denmark)

Olesen, Arne Vestergaard; Forsberg, René; Keller, K.

2000-01-01

In June 1998 National Survey and Cadastre Denmark (KMS) carried out an airborne gravity survey over the Polar Sea to the north of Greenland. A Twin Otter from Greenlandair, equipped with autopilot and additional fuel tanks, was employed for the survey. A modified marine LaCoste & Romberg gravimet...

Antenatal management of twin-twin transfusion syndrome and twin anemia-polycythemia sequence.

Science.gov (United States)

Slaghekke, Femke; Zhao, Depeng P; Middeldorp, Johanna M; Klumper, Frans J; Haak, Monique C; Oepkes, Dick; Lopriore, Enrico

2016-08-01

Twin-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS) are severe complications in monochorionic twin pregnancies associated with high mortality and morbidity risk if left untreated. Both diseases result from imbalanced inter-twin blood transfusion through placental vascular anastomoses. This review focuses on the differences in antenatal management between TTTS and TAPS. Expert commentary: The optimal management for TTTS is fetoscopic laser coagulation of the vascular anastomoses, preferably using the Solomon technique in which the whole vascular equator is coagulated. The Solomon technique is associated with a reduction of residual anastomosis and a reduction in post-operative complications. The optimal management for TAPS is not clear and includes expectant management, intra-uterine transfusion with or without partial exchange transfusion and fetoscopic laser surgery.

A Possible Twin: The 1960s Twin Study Revisited/Twin Research: Twin-to-Twin Heart Transplantation; Distinguishing Monozygotic Twins; Twin Conceptions via Oocyte Donation; Factors Affecting Craniofacial Traits/In the Media: Triplet Delivery in the UK; Conjoined Twins and the Concept of Self; Colombian Twin Trainers; Skin Grafting to Save an Identical Co-Twin; Lack of Physical Flaws in Dolly the Cloned Sheep; Possible Conjoined Twins of Opposite-Sex; Passing of the Remaining Twin From the World's Longest Separated Pair.

Science.gov (United States)

Segal, Nancy L

2018-04-01

This article begins with the story of a 51-year-old Los Angeles, California man, Justin Goldberg, whose daughter caught a glimpse of his striking look-alike at a popular market. Many people have so-called doppelgängers, but this occurrence is especially intriguing - the individual in question, born in New York City in the mid-1960s to an unwed mother, was an adoptee placed by the Louise Wise Adoption Agency. This agency, under the guidance of a prominent psychiatrist, decided to place twins in separate homes. Some of these twin children were part of a controversial child development study that was hidden from them and their parents. Next, recent and current twin research on heart transplantation, distinguishing monozygotic co-twins, twin conceptions via oocyte donation and factors affecting craniofacial traits are summarized. The article concludes with highlights on twins in the media, specifically, a triplet delivery in the United Kingdom, self-concept and consciousness in conjoined twins, Colombian twin trainers, skin grafting to save an identical co-twin, lack of physical flaws in Dolly the cloned sheep, possible opposite-sex conjoined twins, and the passing of the remaining twin from the world's longest separated pair.

Short- and long-term perinatal outcome in twin pregnancies affected by weight discordance

DEFF Research Database (Denmark)

Vedel, Cathrine; Oldenburg, Anna; Worda, Katharina

2017-01-01

INTRODUCTION: The objective was to investigate the association between chorionicity-specific intertwin birthweight discordance and adverse outcomes including long-term follow up at 6, 18, and 48-60 months after term via Ages and Stages Questionnaire. MATERIAL AND METHODS: In this secondary analysis...... outcomes. Ages and Stages Questionnair scores were compared using the method of generalized estimating equation to account for the correlation within twins. RESULTS: The 75th and 90th percentiles for birthweight discordance were 14.8 and 21.4% for monochorionic and 16.0 and 23.8% for dichorionic twins...

Highlights from the 15th International Congress of Twin Studies/Twin Research: Differentiating MZ Co-twins Via SNPs; Mistaken Infant Twin-Singleton Hospital Registration; Narcolepsy With Cataplexy; Hearing Loss and Language Learning/Media Mentions: Broadway Musical Recalls Conjoined Hilton Twins; High Fashion Pair; Twins Turn 102; Insights From a Conjoined Twin Survivor.

Science.gov (United States)

Segal, Nancy L

2015-02-01

Highlights from the 15th International Congress of Twin Studies are presented. The congress was held November 16-19, 2014 in Budapest, Hungary. This report is followed by summaries of research addressing the differentiation of MZ co-twins by single nucleotide polymorphisms (SNPs), an unusual error in infant twin-singleton hospital registration, twins with childhood-onset narcolepsy with cataplexy, and the parenting effects of hearing loss in one co-twin. Media interest in twins covers a new Broadway musical based on the conjoined twins Violet and Daisy Hilton, male twins becoming famous in fashion, twins who turned 102 and unique insights from a conjoined twin survivor. This article is dedicated to the memory of Elizabeth (Liz) Hamel, DZA twin who met her co-twin for the first time at age seventy-eight years. Liz and her co-twin, Ann Hunt, are listed in the 2015 Guinness Book of Records as the longest separated twins in the world.

Mitochondrial DNA Copy Number in Sleep Duration Discordant Monozygotic Twins.

Science.gov (United States)

Wrede, Joanna E; Mengel-From, Jonas; Buchwald, Dedra; Vitiello, Michael V; Bamshad, Michael; Noonan, Carolyn; Christiansen, Lene; Christensen, Kaare; Watson, Nathaniel F

2015-10-01

Mitochondrial DNA (mtDNA) copy number is an important component of mitochondrial function and varies with age, disease, and environmental factors. We aimed to determine whether mtDNA copy number varies with habitual differences in sleep duration within pairs of monozygotic twins. Academic clinical research center. 15 sleep duration discordant monozygotic twin pairs (30 twins, 80% female; mean age 42.1 years [SD 15.0]). Sleep duration was phenotyped with wrist actigraphy. Each twin pair included a "normal" (7-9 h/24) and "short" (sleeping twin. Fasting peripheral blood leukocyte DNA was assessed for mtDNA copy number via the n-fold difference between qPCR measured mtDNA and nuclear DNA creating an mtDNA measure without absolute units. We used generalized estimating equation linear regression models accounting for the correlated data structure to assess within-pair effects of sleep duration on mtDNA copy number. Mean within-pair sleep duration difference per 24 hours was 94.3 minutes (SD 62.6 min). We found reduced sleep duration (β = 0.06; 95% CI 0.004, 0.12; P sleep efficiency (β = 0.51; 95% CI 0.06, 0.95; P sleep duration was associated with a decrease in mtDNA copy number of 0.06. Likewise, a 1% decrease in actigraphy-defined sleep efficiency was associated with a decrease in mtDNA copy number of 0.51. Reduced sleep duration and sleep efficiency were associated with reduced mitochondrial DNA copy number in sleep duration discordant monozygotic twins offering a potential mechanism whereby short sleep impairs health and longevity through mitochondrial stress. © 2015 Associated Professional Sleep Societies, LLC.

Designing Mission Operations for the Gravity Recovery and Interior Laboratory Mission

Science.gov (United States)

Havens, Glen G.; Beerer, Joseph G.

2012-01-01

NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission, to understand the internal structure and thermal evolution of the Moon, offered unique challenges to mission operations. From launch through end of mission, the twin GRAIL orbiters had to be operated in parallel. The journey to the Moon and into the low science orbit involved numerous maneuvers, planned on tight timelines, to ultimately place the orbiters into the required formation-flying configuration necessary. The baseline GRAIL mission is short, only 9 months in duration, but progressed quickly through seven very unique mission phases. Compressed into this short mission timeline, operations activities and maneuvers for both orbiters had to be planned and coordinated carefully. To prepare for these challenges, development of the GRAIL Mission Operations System began in 2008. Based on high heritage multi-mission operations developed by NASA's Jet Propulsion Laboratory and Lockheed Martin, the GRAIL mission operations system was adapted to meet the unique challenges posed by the GRAIL mission design. This paper describes GRAIL's system engineering development process for defining GRAIL's operations scenarios and generating requirements, tracing the evolution from operations concept through final design, implementation, and validation.

Molecular dynamics simulation of albite twinning and pericline twinning in low albite

International Nuclear Information System (INIS)

Li, Bin; Knowles, Kevin M

2013-01-01

Two twinning laws, the albite law and the pericline law, are the predominant growth twinning modes in triclinic plagioclase feldspars such as low albite, NaAlSi 3 O 8 , in which the aluminum and silicon atoms are in an ordered arrangement on the tetrahedral sites of the aluminosilicate framework. In the terminology used formally to describe deformation twinning in a triclinic lattice, these twin laws can be described as Type I and Type II twin laws, respectively, with the pericline twin law being conjugate to the albite twin law. In this study, twin boundaries have been constructed for low albite according to these two twinning laws and studied by molecular dynamics simulation. The results show that suitably constructed twin boundary models are quite stable for both albite twinning and pericline twinning during molecular dynamics simulation. The calculated twin boundary energy of an albite twin is significantly lower than that of a pericline twin, in accord with the experimental observation that albite twinning is the more commonly observed mode seen in plagioclase feldspars. The results of the molecular dynamics simulations also agree with conclusions from the prior work of Starkey that glide twinning in low albite is not favoured energetically. (paper)

Art for twins: Yorùbá artists and their statues/twin research studies: twins' education and conceptions; diurnal preference; inherited eye diseases; ultrasound counseling when twins are conjoined/popular twin reports: twin sisters (the film); rare pregnancy; diet test; French twins reared apart and reunited.

Science.gov (United States)

Segal, Nancy L

2014-06-01

The Yorùbá of Nigeria are well known for their high twinning rate and the statues they create to commemorate deceased twins. An impressive collection of this artwork was displayed at the University of California's Fowler Museum in Los Angeles between October 13, 2013 and March 2, 2014. An overview of this exhibit is provided. Next, twin research on maternal education and conception, diurnal preference, inherited eye diseases, and ultrasound counseling for couples with conjoined twins are briefly summarized. This article concludes with a discussion of media-based items related to twins. The topics include an award-winning twin film, a rare pregnancy, a diet test, and the separation and chance reunion of monozygotic female twins.

Residence time distribution in twin-screw extruders

NARCIS (Netherlands)

Jager, T.

1992-01-01

For the twin-screw extruders used in the food industry at short time high temperature processes the knowledge of their reactor properties is incomplete for mass- and heat flow. Therefore each process change such as: scale-up or product development requires a great number of measurements

Management of Conjoined Twins During Neonatal Period

African Journals Online (AJOL)

HussamHassan

Background/Purpose: Conjoined twins are rare and complex anomalies of the newborn. ... The short term postoperative follow up revealed uneventful course of 6 children resulting from ... sex and karyotype 3. ... revealed vertebral bodies, brain tissue occupying the ... continued for 8 hours during which the right and left.

Monozygotic twin discordant for Down syndrome: mos 47,XX,+21/46,XX and 46,XX.

Science.gov (United States)

Choi, Sun Ah; Ko, Jung Min; Shin, Choong Ho; Yang, Sei Won; Choi, Jin Sun; Oh, Sun Kyung

2013-08-01

Monozygotic twins, developed from a single zygote, are almost identical in clinical phenotype and concordant karyotypes. Monozygotic twins with discordant karyotypes are thought to be quite rare. Here, we report monochorionic-diamniotic twins discordant for Down syndrome. On findings of prenatal ultrasonography, nuchal translucency thickness was different between twins, and suggested that one of the twins was at high risk for having chromosomal abnormalities including Down syndrome. The twins were monochorionic-diamniotic; therefore, chorionic villi sampling of the common placenta was performed. The karyotype of the chorionic villi cells was 46,XX, and pregnancy was maintained. After delivery, dysmorphic clinical features suggesting Down syndrome were found in one of the twins, while the other twin showed a morphologically normal appearance. Karyotypes of peripheral blood leukocytes were repeatedly normal in the dysmorphic twin; however, the karyotype of skin fibroblasts from the dysmorphic twin indicated Down syndrome mosaicism; 47,XX,+21[99]/46,XX[2]. The karyotype of skin fibroblasts from the morphologically normal twin was 46,XX. Monozygosity of the twins was confirmed by a short tandem repeat analysis using 16 polymorphic markers. A mitotic nondisjunction followed by the twinning would explain the discordant karyotypes between monozygotic twins.

Therapeutic modalities of twin to twin transfusion syndrome

Directory of Open Access Journals (Sweden)

Šulović N.

2015-01-01

Full Text Available Twin to twin transfusion syndrome (TTTTS accounts for approximately 10% of monochorionic twin pregnancies and, if left untreated, is associated with high morbidity and mortality rate. A net transfusion of blood flow from one fetus (donor twin to the other (recipient twin via placental vascular anastomoses has been supposed as the major etiology of TTTTS. The donor twin becomes hypovolemic and oliguria, oligohydramnios, and a variable degree of growth restriction develop, whereas the recipient twin manifests polyuria, polyhydramnios, and hydrops in response to hypervolemia. TTTTS can be treated by either serial amniocentesis or selective fetoscopic laser coagulation of the communicating vessels. The rationale for removal of large volumes of amniotic fluid is to prevent preterm delivery secondary to polyhydramnios and to improve fetal circulation by reducing pressure on the chorionic plate. On the other hand, the goal of laser therapy is to occlude vascular anastomoses, thereby interrupting intertwin blood exchange. Although laser treatment is associated with increased survival rate and reduced neurologic complications, compared with amnioreduction, it requires highly specialized centers, whereas serial amniocentesis has the advantage of being performed worldwide. Therefore, the optimal treatment for pregnancies complicated with TTTTS is still controversial.

Greenland inland ice melt-off: Analysis of global gravity data from the GRACE satellites

DEFF Research Database (Denmark)

Nielsen, Allan Aasbjerg; Andersen, Ole Baltazar; Svendsen, Peter L.

2011-01-01

This paper gives an introductory analysis of gravity data from the GRACE (Gravity Recovery And Climate Experiment) twin satellites. The data consist of gravity data in the form of 10-day maximum values of 1◦ by 1◦ equivalent water height (EWH) in meters starting at 29 July 2002 and ending at 25...... August 2010. Results focussing on Greenland show statistically significant mass loss interpreted as inland ice melt-off to the SE and NW with an acceleration in the melt-off occurring to the NW and a possible deceleration to the SE. Also, there are strong indications of a transition taking place...

Twin Research and the Arts: Interconnections / Twin Research: Twin Studies of Sexual Orientation; A Historical Biological Twin Gem; GWAS Approach to Who Has Twins / Newsworthy: Twins on College Campuses; 'Brainprint': Personal Identification by Brain Waves.

Science.gov (United States)

Segal, Nancy L

2016-08-01

The interrelatedness between twin research and the arts is explored via a new play about a famous case. In the 1960s, identical twin David Bruce Reimer was accidentally castrated as an infant during circumcision to correct a urinary problem. The decision to raise him as a girl, and the consequences of that decision, are explored in the new theatrical production of Boy. Other examples of the arts mirroring science, and vice versa, are described. Next, brief reviews and summaries of twin research on sexual orientation, 1860s' knowledge of placental arrangements and twinning mechanisms, and genes underlying multiple birth conception and fertility related measures are provided. This article concludes with a look at twins on college campuses and the identification of individuals by their brain waves. A correction and clarification regarding my article on the Brazilian Twin Registry in the last issue of THG (Segal, 2016) is also provided.

Intragranular twinning, detwinning, and twinning-like lattice reorientation in magnesium alloys

International Nuclear Information System (INIS)

Wu, Wei; Gao, Yanfei; Li, Nan; Parish, Chad M.; Liu, Wenjun; Liaw, Peter K.; An, Ke

2016-01-01

Deformation twinning plays a critical role on improving metals or alloys ductility, especially for hexagonal close-packed materials with low symmetry crystal structure. A rolled Mg alloy was selected as a model system to investigate the extension twinning behaviors and characteristics of parent-twin interactions by nondestructive in situ 3D synchrotron X-ray microbeam diffraction. Besides twinning-detwinning process, the “twinning-like” lattice reorientation process was captured within an individual grain inside a bulk material during the strain reversal. The distributions of parent, twin, and reorientated grains and sub-micron level strain variation across the twin boundary are revealed. A theoretical calculation of the lattice strain confirms that the internal strain distribution in parent and twinned grains correlates with the experimental setup, grain orientation of parent, twin, and surrounding grains, as well as the strain path changes. The study suggests a novel deformation mechanism within the hexagonal close-packed structure that cannot be determined from surface-based characterization methods.

The neonatal outcome in twin versus triplet and quadruplet pregnancies

Directory of Open Access Journals (Sweden)

Fatemeh Nasseri

2009-02-01

Full Text Available

• BACKGROUND: To assess the risk of neonatal mortality and morbidity in twin, triplet and quadruplet pregnancies.
• METHODS: In a retrospective study, the neonatal outcome of all twin, triplet and quadruplet gestations delivered from October 2001 to September 2006 was reviewed. The neonatal outcome of triples and quadruplets was compared with a matched group of twins for gestational age.
• RESULTS: During a 5-year period, 511 sets of twin pregnancies, 42 sets of triplet and 5 sets of quadruplet pregnancies were studied. The mean of gestational age for twins, triplets and quadruplets were 33.92 ± 3.5 weeks, 30.92 ± 3.8 weeks and 31.60 ± 2.0 weeks, respectively, (P = 0.0001. Triplets and quadruplets weighed less than twins, (P = 0.0001. Neonatal mortality was 13.5% for twins, 26.8% for triplets and 30% for quadruplets. In vitro fertilization, use of ovulation induction agents, and cesarean delivery in the women with triplet and quadruplet were significantly higher than in those with twin pregnancies, (P = 0.0001. The mean age of mothers with triplets and quadruplets was significantly higher than with twins (P = 0.026. There was not a significant difference in respiratory and non-respiratory short outcomes between triplets, quadruplets and twins when matched for gestational age. Apgar score at 1 and 5 minutes was significantly lower in triplets and quadruplets than twins. There was no influence of birth order on neonatal mortality of triplet pregnancy. Neonatal mortality of triplet births was significantly decreased over the 5 years of the study period.
• CONCLUSIONS: Triplets and quadruplets have a similar neonatal outcome as twins when matched for gestational age. There is no influence of birth on the neonatal mortality of triplet pregnancy. It appears that outcome is mainly dependent on gestational age.
• KEYWORDS: Neonatal

• Simulations of stress-induced twinning and de-twinning: A phase field model

  International Nuclear Information System (INIS)

  Hu Shenyang; Henager, Chuck H.; Chen Longqing

  2010-01-01

  Twinning in certain metals or under certain conditions is a major plastic deformation mode. Here we present a phase field model to describe twin formation and evolution in a polycrystalline fcc metal under loading and unloading. The model assumes that twin nucleation, growth and de-twinning is a process of partial dislocation nucleation and slip on successive habit planes. Stacking fault energies, energy pathways (γ surfaces), critical shear stresses for the formation of stacking faults and dislocation core energies are used to construct the thermodynamic model. The simulation results demonstrate that the model is able to predict the nucleation of twins and partial dislocations, as well as the morphology of the twin nuclei, and to reasonably describe twin growth and interaction. The twin microstructures at grain boundaries are in agreement with experimental observation. It was found that de-twinning occurs during unloading in the simulations, however, a strong dependence of twin structure evolution on loading history was observed.

• Twins and Kindergarten Separation: Divergent Beliefs of Principals, Teachers, Parents, and Twins

  Science.gov (United States)

  Gordon, Lynn Melby

  2015-01-01

  Should principals enforce mandatory separation of twins in kindergarten? Do school separation beliefs of principals differ from those of teachers, parents of twins, and twins themselves? This survey questioned 131 elementary principals, 54 kindergarten teachers, 201 parents of twins, and 112 twins. A majority of principals (71%) believed that…

• Twin-twin transfusion syndrome: etiology, severity and rational management

  NARCIS (Netherlands)

  van Gemert, M. J.; Umur, A.; Tijssen, J. G.; Ross, M. G.

  2001-01-01

  The twin-twin transfusion syndrome is a serious complication of monochorionic twin pregnancies. Partly as a result of an inadequate understanding of the pathophysiology of the syndrome, there is a lack of consensus in clinical management. We sought to review the available information on the etiology

• The mobility of growth twins synthesized by sputtering: Tailoring the twin thickness

  International Nuclear Information System (INIS)

  Velasco, Leonardo; Hodge, Andrea M.

  2016-01-01

  The current work presents a protean twin thickness contour zone map that illustrates how the nucleation and the mobility of twin boundaries affects the twin thickness of sputtered films. The twin thickness contour zone map can be used as a versatile guide to synthesize fully nanotwinned films with tailored twin thicknesses in materials with a wide range of stacking fault energies. The nucleation and mobility of twin boundaries was studied in four Cu alloys of different compositions (Cu-6wt.%Al, Cu-4wt.%Al, Cu-2wt.%Al, and Cu-10wt.%Ni), having stacking fault energies ranging from 6 mJ/m 2 to 60 mJ/m 2 . The films were synthesized by magnetron sputtering and characterized by transmission electron microscopy, where the twin thickness varied from 2 nm to 35 nm. Our experimental results show that it is possible to control the twin thickness. Three main mechanisms are explained to describe twin nucleation and twin boundary mobility, which are correlated to the interplay of specific sputtering conditions and the deposition temperature.

• Scaling in quantum gravity

  Directory of Open Access Journals (Sweden)

  J. Ambjørn

  1995-07-01

  Full Text Available The 2-point function is the natural object in quantum gravity for extracting critical behavior: The exponential falloff of the 2-point function with geodesic distance determines the fractal dimension dH of space-time. The integral of the 2-point function determines the entropy exponent γ, i.e. the fractal structure related to baby universes, while the short distance behavior of the 2-point function connects γ and dH by a quantum gravity version of Fisher's scaling relation. We verify this behavior in the case of 2d gravity by explicit calculation.

• Linking granulation performance with residence time and granulation liquid distributions in twin-screw granulation: An experimental investigation

  DEFF Research Database (Denmark)

  Kumar, Ashish; Alakarjula, Maija; Vanhoorne, Valérie

  2016-01-01

  Twin-screw granulation is a promising wet granulation technique for the continuous manufacturing of pharmaceutical solid dosage forms. A twin screw granulator displays a short residence time. Thus, the solid-liquid mixing must be achieved quickly by appropriate arrangement of transport and kneading...

• The Qingdao Twin Registry

  DEFF Research Database (Denmark)

  Duan, Haiping; Ning, Feng; Zhang, Dongfeng

  2013-01-01

  In 1998, the Qingdao Twin Registry was initiated as the main part of the Chinese National Twin Registry. By 2005, a total of 10,655 twin pairs had been recruited. Since then new twin cohorts have been sampled, with one longitudinal cohort of adolescent twins selected to explore determinants of me...

• Twins and non-twin siblings: different estimates of shared environmental influence in early childhood.

  Science.gov (United States)

  Koeppen-Schomerus, Gesina; Spinath, Frank M; Plomin, Robert

  2003-04-01

  Twin studies typically indicate shared environmental influence for cognitive abilities, especially in early childhood. However, across studies, DZ twin correlations tend to be greater than non-twin sibling correlations, suggesting that twin estimates of shared environment are to some extent specific to twins. We tested this hypothesis in a sample of more than 1800 MZ and 1800 same-sex DZ pairs from the Twins Early Development Study (TEDS), a study of twins born in England and Wales in 1994 and 1995. For this analysis, we obtained comparable data from more than 130 same-sex younger siblings of the twins. Twins and their younger siblings were assessed for language, cognitive abilities and behavior problems by their parents at 2 and 3 years of age. For language and cognitive measures at both 2 and 3 years, but not for behavior problems, estimates of shared environment were more than twice as large for twins as compared to non-twin siblings. We conclude that about half of twin study estimates of shared environment for cognitive abilities in early childhood are specific to twins. Although many possibilities exist for explaining the special shared environment effect for twins, we suggest that cognitive-relevant experiences that are not shared by siblings are shared by twins because they are exactly the same age.

• Why is gravity so weak?

  International Nuclear Information System (INIS)

  Goradia, S.G.

  2006-01-01

  Why is gravity weak? Gravity is plagued with this and many other questions. After decades of exhausting work we do not have a clear answer. In view of this fact it will be shown in the following pages that there are reasons for thinking that gravity is just a composite force consisting of the long-range manifestations of short range nuclear forces that are too tiny to be measured at illuminated or long ranges by particle colliders. This is consistent with Einstein's proposal in 1919

• Effect of co-twin gender on neurodevelopmental symptoms: a twin register study.

  Science.gov (United States)

  Eriksson, Jonna Maria; Lundström, Sebastian; Lichtenstein, Paul; Bejerot, Susanne; Eriksson, Elias

  2016-01-01

  Autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) are neurodevelopmental disorders thought to have both genetic and environmental causes. It has been hypothesized that exposure to elevated levels of prenatal testosterone is associated with elevated traits of ASD and ADHD. Assuming that testosterone levels from a dizygotic male twin fetus may lead to enhanced testosterone exposure of its co-twins, we aimed to test the prenatal testosterone hypothesis by comparing same-sex with opposite-sex dizygotic twins with respect to neurodevelopmental symptoms. Neuropsychiatric traits were assessed in a population-based twin cohort from the Child and Adolescent Twin Study in Sweden (CATSS). Parental interviews were conducted for 16,312 dizygotic twins, 9 and 12 years old, with the Autism-Tics, ADHD, and other Comorbidities inventory (A-TAC). Girls with a female co-twin had an increased risk of reaching the cut-off score for ADHD compared with girls with a male co-twin. Both boys and girls with a female co-twin displayed a larger number of traits related to attention deficit and repetitive and stereotyped behaviors than those with a male twin. In girls, this also extended to social interaction and the combined measures for ASD and ADHD, however, with small effect sizes. Our results are reverse to what would have been expected from the prenatal testosterone hypothesis but consistent with a previous study of ASD and ADHD traits in dizygotic twins. The seemingly protective effect for girls of having a twin brother may be an effect of parent report bias, but may also be an unexpected effect of sharing the intrauterine environment with a male co-twin.

• Attractiveness Differences Between Twins Predicts Evaluations of Self and Co-Twin

  Science.gov (United States)

  Principe, Connor P.; Rosen, Lisa H.; Taylor-Partridge, Teresa; Langlois, Judith H.

  2012-01-01

  One of the most consistent findings in psychology shows that people prefer and make positive attributions about attractive compared with unattractive people. The goal of the current study was to determine the power of attractiveness effects by testing whether these social judgments are made where attractiveness differences are smallest: between twins. Differences in facial attractiveness predicted twins’ evaluations of self and their co-twin (n = 158; 54 male). In twin pairs, the more attractive twin judged their less attractive sibling as less physically attractive, athletic, socially competent, and emotionally stable. The less attractive twin did the reverse. Given that even negligible differences in facial attractiveness predicted self and co-twin attitudes, these results provide the strongest test yet of appearance-based stereotypes. PMID:23467329

Giant narrowband twin-beam generation along the pump-energy propagation direction

Science.gov (United States)

Pérez, Angela M.; Spasibko, Kirill Yu; Sharapova, Polina R.; Tikhonova, Olga V.; Leuchs, Gerd; Chekhova, Maria V.

2015-07-01

Walk-off effects, originating from the difference between the group and phase velocities, limit the efficiency of nonlinear optical interactions. While transverse walk-off can be eliminated by proper medium engineering, longitudinal walk-off is harder to avoid. In particular, ultrafast twin-beam generation via pulsed parametric down-conversion and four-wave mixing is only possible in short crystals or fibres. Here we show that in high-gain parametric down-conversion, one can overcome the destructive role of both effects and even turn them into useful tools for shaping the emission. In our experiment, one of the twin beams is emitted along the pump Poynting vector or its group velocity matches that of the pump. The result is markedly enhanced generation of both twin beams, with the simultaneous narrowing of angular and frequency spectrum. The effect will enable efficient generation of ultrafast twin photons and beams in cavities, waveguides and whispering-gallery mode resonators.

Gravity model improvement investigation. [improved gravity model for determination of ocean geoid

Science.gov (United States)

Siry, J. W.; Kahn, W. D.; Bryan, J. W.; Vonbun, F. F.

1973-01-01

This investigation was undertaken to improve the gravity model and hence the ocean geoid. A specific objective is the determination of the gravity field and geoid with a space resolution of approximately 5 deg and a height resolution of the order of five meters. The concept of the investigation is to utilize both GEOS-C altimeter and satellite-to-satellite tracking data to achieve the gravity model improvement. It is also planned to determine the geoid in selected regions with a space resolution of about a degree and a height resolution of the order of a meter or two. The short term objectives include the study of the gravity field in the GEOS-C calibration area outlined by Goddard, Bermuda, Antigua, and Cape Kennedy, and also in the eastern Pacific area which is viewed by ATS-F.

Monochorionic twin pregnancies

NARCIS (Netherlands)

Hack, K.E.A.

2008-01-01

Following widespread application of assisted reproductive technology modalities and the increased age of motherhood, the incidence of twin gestations has increased markedly. Twins are either monozygotic or dizygotic. Dizygotic (i.e. fraternal) twins result from the fertilization of two different

Multi(scale)gravity: a telescope for the micro-world

International Nuclear Information System (INIS)

Kogan, I.I.

2001-01-01

A short review of modern status of multi-gravity, i.e. modification of gravity at both short and large distances is given. Usually embedding of standard model and general relativity into any multidimensional construction gives rise to all possible sorts of new effects in a micro-world but we can also get a very drastic modification of these laws of gravity at ultra-large scale. One of the reason why multi-gravity can modify CMB (cosmic microwave background) is that it leads to a large distance modification of the curvature. One of very striking features of multi-gravity is that it gives us a some sort of a dark matter whose origin is that it is just matter from other branes. The author shows that on a 5-dimensional case and at large distances, multi-gravity opens a window in extra dimensions and gravitationally matter which is localized on other branes can be felt. (A.C.)

Estimating twin concordance for bivariate competing risks twin data

DEFF Research Database (Denmark)

Scheike, Thomas; Holst, Klaus K.; Hjelmborg, Jacob B.

2014-01-01

For twin time-to-event data, we consider different concordance probabilities, such as the casewise concordance that are routinely computed as a measure of the lifetime dependence/correlation for specific diseases. The concordance probability here is the probability that both twins have experience...... events with the competing risk death. We thus aim to quantify the degree of dependence through the casewise concordance function and show a significant genetic component...... the event of interest. Under the assumption that both twins are censored at the same time, we show how to estimate this probability in the presence of right censoring, and as a consequence, we can then estimate the casewise twin concordance. In addition, we can model the magnitude of within pair dependence...... over time, and covariates may be further influential on the marginal risk and dependence structure. We establish the estimators large sample properties and suggest various tests, for example, for inferring familial influence. The method is demonstrated and motivated by specific twin data on cancer...

Modeling acardiac twin pregnancies

NARCIS (Netherlands)

de Groot, Rosa; van den Wijngaard, Jeroen P. H. M.; Umur, Asli; Beek, Johan F.; Nikkels, Peter G. J.; van Gemert, Martin J. C.

2007-01-01

Acardiac twin pregnancies are a rare but severe complication of monochorionic twinning, where the acardiac twin lacks cardiac function but nevertheless grows during pregnancy because it is perfused by the pump twin through a set of placental arterioarterial and venovenous anastomoses. Because the

Personality and birth order in monozygotic twins adopted apart: a test of Sulloway's theory; Research Reviews: twin births and cancer risk in mothers, male sexual dysfunction, twin study of ultimatum game behavior; Human Interest: 'The Land of Twins', twin-like reunion-I, twin-like reunion-II.

Science.gov (United States)

Segal, Nancy L

2008-02-01

A brief overview of Sulloway's (1996) theory of birth order and personality is presented. A reared apart twin approach for testing his personality findings regarding openness to experience and conscientiousness in first borns and later borns is described. This is followed by summaries of three recent twin studies. The topics include cancer risk in mother of twins, sexual dysfunction in males and responder behavior during ultimatum games. This article concludes with a discussion of twinning rates and rituals among the Yoruba of western Nigeria, and descriptions of two unusual reunions between siblings and twins.

UV caps, IR modification of gravity, and recovery of 4D gravity in regularized braneworlds

International Nuclear Information System (INIS)

Kobayashi, Tsutomu

2008-01-01

In the context of six-dimensional conical braneworlds we consider a simple and explicit model that incorporates long-distance modification of gravity and regularization of codimension-2 singularities. To resolve the conical singularities we replace the codimension-2 branes with ringlike codimension-1 branes, filling in the interiors with regular caps. The six-dimensional Planck scale in the cap is assumed to be much greater than the bulk Planck scale, which gives rise to the effect analogous to brane-induced gravity. Weak gravity on the regularized brane is studied in the case of a sharp conical bulk. We show by a linear analysis that gravity at short distances is effectively described by the four-dimensional Brans-Dicke theory, while the higher dimensional nature of gravity emerges at long distances. The linear analysis breaks down at some intermediate scale, below which four-dimensional Einstein gravity is shown to be recovered thanks to the second-order effects of the brane bending.

The nature of pseudo-twinning modes on the basis of a twin classification scheme

International Nuclear Information System (INIS)

Singh, Jung B.; Sundararaman, M.; Krishnan, M.

2011-01-01

Pseudo-twins can form in ordered structures under high stress conditions. These twins are defined by lattice sites that are at twin positions but are incorrectly occupied by different species of atoms. The present note discusses if it is possible to further classify pseudo-twins into different modes based on the nature of associated twinning elements.

11 T Twin-Aperture Nb$_3$Sn Dipole Development for LHC Upgrades

CERN Document Server

Zlobin, A V; Apollinari, G; Auchmann, B; Barzi, E; Izquierdo Bermudez, S; Bossert, R; Buehler, M; Chlachidze, G; DiMarco, J; Karppinen, M; Nobrega, F; Novitski, I; Rossi, L; Smekens, D; Tartaglia, M; Turrioni, D; Velev, Genadi

2015-01-01

FNAL and CERN are developing a twin-aperture 11 T Nb$_{3}$Sn dipole suitable for installation in the LHC. This paper describes the design and parameters of the 11 T dipole developed at FNAL for the LHC upgrades in both single-aperture and twin-aperture configurations, and presents details of the constructed dipole models. Results of studies of magnet quench performance, quench protection and magnetic measurements performed using short 1 m long coils in the dipole mirror and single-aperture configurations are reported and discussed.

11 T Twin-Aperture Nb$_3$Sn Dipole Development for LHC Upgrades

Energy Technology Data Exchange (ETDEWEB)

Zlobin, A. V. [Fermilab; Andreev, N. [Fermilab; Apollinari, G. [Fermilab; Auchmann, B. [CERN; Barzi, E. [Fermilab; Izquierdo Bermudez, S. [CERN; Bossert, R. [Fermilab; Buehler, M. [Fermilab; Chlachidze, G. [Fermilab; DiMarco, J. [Fermilab; Karppinen, M. [CERN; Nobrega, F. [Fermilab; Novitski, I. [CERN; Rossi, L. [CERN; Smekens, D. [CERN; Tartaglia, M. [Fermilab; Turrioni, D. [Fermilab; Velev, Genadi [Fermilab

2015-01-01

FNAL and CERN are developing a twin-aperture 11 T Nb3Sn dipole suitable for installation in the LHC. This paper describes the design and parameters of the 11 T dipole developed at FNAL for the LHC upgrades in both single-aperture and twin-aperture configurations, and presents details of the constructed dipole models. Results of studies of magnet quench performance, quench protection and magnetic measurements performed using short 1 m long coils in the dipole mirror and single-aperture configurations are reported and discussed.

Twin-to-twin transfusion syndrome : from placental anastomoses to long-term outcome

NARCIS (Netherlands)

Lopriore, Enrico

2006-01-01

Twin-to-twin transfusion syndrome (TTTS) is a severe complication of monochorionic twin pregnancies associated with high perinatal mortality and morbidity rates. Placental vascular anastomoses, almost invariably present in monochorionic placentas, are the essential anatomical substrate for the

Is that me or my twin? Lack of self-face recognition advantage in identical twins.

Directory of Open Access Journals (Sweden)

Matteo Martini

Full Text Available Despite the increasing interest in twin studies and the stunning amount of research on face recognition, the ability of adult identical twins to discriminate their own faces from those of their co-twins has been scarcely investigated. One's own face is the most distinctive feature of the bodily self, and people typically show a clear advantage in recognizing their own face even more than other very familiar identities. Given the very high level of resemblance of their faces, monozygotic twins represent a unique model for exploring self-face processing. Herein we examined the ability of monozygotic twins to distinguish their own face from the face of their co-twin and of a highly familiar individual. Results show that twins equally recognize their own face and their twin's face. This lack of self-face advantage was negatively predicted by how much they felt physically similar to their co-twin and by their anxious or avoidant attachment style. We speculate that in monozygotic twins, the visual representation of the self-face overlaps with that of the co-twin. Thus, to distinguish the self from the co-twin, monozygotic twins have to rely much more than control participants on the multisensory integration processes upon which the sense of bodily self is based. Moreover, in keeping with the notion that attachment style influences perception of self and significant others, we propose that the observed self/co-twin confusion may depend upon insecure attachment.

Twin RSA

OpenAIRE

Lenstra, Arjen K.; Weger, De; Benjamin, M. M.

2005-01-01

We introduce Twin RSA, pairs of RSA moduli (n, n+ 2), and formulate several questions related to it. Our main questions are: is Twin RSA secure, and what is it good for? © Springer-Verlag Berlin Heidelberg 2005.

Infinite derivative gravity : non-singular cosmology & blackhole solutions

NARCIS (Netherlands)

Mazumdar, Anupam

2017-01-01

Both Einstein's theory of General Relativity and Newton's theory of gravity possess a short dis- tance and small time scale catastrophe. The blackhole singularity and cosmological Big Bang singularity problems highlight that current theories of gravity are incomplete description at early times and

Sports pairs: insights on athletic talent; research reviews: twins with leukemia; parents and twins.

Science.gov (United States)

Segal, Nancy L

2007-06-01

Twin research exploring genetic and environmental influences on athletic interests and talents is reviewed. Illustrative examples of twin athletes representing a variety of sports activities are presented. This is followed by an overview of twin studies offering critical insights into the onset and progress of leukemia. In the last section, timely events involving twins and parents of twins will be described--each case provides a new look at an old question.

The Brazilian Twin Registry.

Science.gov (United States)

Ferreira, Paulo H; Oliveira, Vinicius C; Junqueira, Daniela R; Cisneros, Lígia C; Ferreira, Lucas C; Murphy, Kate; Ordoñana, Juan R; Hopper, John L; Teixeira-Salmela, Luci F

2016-12-01

The Brazilian Twin Registry (BTR) was established in 2013 and has impelled twin research in South America. The main aim of the initiative was to create a resource that would be accessible to the Brazilian scientific community as well as international researchers interested in the investigation of the contribution of genetic and environmental factors in the development of common diseases, phenotypes, and human behavior traits. The BTR is a joint effort between academic and governmental institutions from Brazil and Australia. The collaboration includes the Federal University of Minas Gerais (UFMG) in Brazil, the University of Sydney and University of Melbourne in Australia, the Australian Twin Registry, as well as the research foundations CNPq and CAPES in Brazil. The BTR is a member of the International Network of Twin Registries. Recruitment strategies used to register twins have been through participation in a longitudinal study investigating genetic and environmental factors for low back pain occurrence, and from a variety of sources including media campaigns and social networking. Currently, 291 twins are registered in the BTR, with data on demographics, zygosity, anthropometrics, and health history having been collected from 151 twins using a standardized self-reported questionnaire. Future BTR plans include the registration of thousands of Brazilian twins identified from different sources and collaborate nationally and internationally with other research groups interested on twin studies.

Twin Loss: Implications for Counselors Working with Surviving Twins.(practice & Theory)

Science.gov (United States)

Withrow, Rebecca; Schwiebert, Valerie L.

2005-01-01

Multiple births are becoming increasingly prevalent due to the use of fertility drugs and women choosing to wait until later life to conceive. With the growth in the twin population, little research has been done to investigate the effects on the grief process when 1 twin dies. Counselors must understand the unique experience of twins to formulate…

Needle twins and right-angled twins in minerals: comparison between experiment and theory

Science.gov (United States)

Salje, E.K.H.; Buckley, A.; Van Tendeloo, G.; Ishibashi, Y.; Nord, G.L.

1998-01-01

Transformation twinning in minerals forms isolated twin walls, intesecting walls with corner junctions, and wedge-shaped twins as elements of hierarchical patterns. When cut perpendicular to the twin walls, the twins have characteristic shapes, right-angled and needle-shaped wall traces, which can be observed by transmission electron microscopy or by optical microscopy. Theoretical geometries of wall shapes recently derived for strain-related systems should hold for most displacive and order-disorder type phase transitions: 1) right-angled twins show curved junctions; 2) needle-shaped twins contain flat wall segments near the needle tip if the elastic behaviour of the mineral is dominated by its anisotroyp; 3) additional bending forces and pinning effects lead to curved walls near the junction that make the needle tip appear more blunt. Bent right-angled twins were analyzed in Gd2(MoO4)3. Linear needle tips were found in WO3, [N(CH3)4]2.ZnBr4 CrAl, BiVO4, GdBa2Cu3O7, and PbZrO. Parabolic tips occur in K2Ba(NO2)4, and GeTe whereas exponential curvatures appear in BaTiO3, KSCN, Pb3(PO4)2, CaTiO3, alkali feldspars, YBa2Cu3O7, and MnAl. The size and shape of the twin microstructure relates to its formation during the phase transition and the subsequent annealing history. The mobility of the twin walls after formation depends not only on the thermal activation but also on the structure of the wall, which may be pinned to impurities on a favorable structural site. Depinnign energies are often large compared with thermal energies for diffusion. This leads to kinetic time scales for twin coarsening that are comparable to geological time scales. Therefore, transformation twins that exhibit needle domains not only indicate that the mineral underwent a structural phase transition but also contain information about its subsequent geological history.

[Panhypopituitarism in one identical twin: the effect of hormone replacement].

Science.gov (United States)

Del Canho, Harrij; van Alfen-van der Velden, Janiëlle; del Canho, Riwka; Otten, Barto

2011-01-01

Panhypopituitarism in childhood is rare. It is even rarer if the disorder appears in a boy with an identical but healthy twin brother. In such a patient it is useful to study the consequences of the hormone disorder and the effect of hormone replacement. A 6-year-old boy saw a paediatrician because of short stature. He was much shorter than his identical twin brother and he had more abdominal fat mass and a smaller penis. Laboratory tests identified hypothyroidism of central origin, in combination with hypocortisolism and growth hormone deficiency. Hormonal replacement resulted in an improvement in growth rate. At the age of 15 years, testosterone therapy was introduced because puberty had not occurred and his growth rate was low. Finally the patient grew a few centimetres taller than his twin brother. In the first year of life, panhypopituitarism has no negative consequences for growth. After this point, growth is clearly delayed. With sufficient replacement growth can completely catch up.

Ventricular strain changes in monochorionic twins with and without twin-to-twin transfusion syndrome.

Science.gov (United States)

Taylor-Clarke, Marisa C; Matsui, Hikoro; Roughton, Michael; Wimalasundera, Ruwan C; Gardiner, Helena M

2013-06-01

The objective of the study was to investigate whether vector velocity imaging (VVI), a non-Doppler speckle tracking ultrasound technology, is feasible in twin pregnancies and can aid management of twin-twin transfusion syndrome (TTTS). Twenty-seven women pregnant with monochorionic diamniotic twins affected by TTTS and 28 monochorionic pregnancies that did not develop TTTS were included in a prospective case-control study at a fetal medicine center. Fetal echocardiograms were recorded with dummy electrocardiography to retain original frame rates when exported for offline speckle tracking analysis using Syngo-VVI software (Siemens Corp, Munich, Germany). Right and left ventricular (LV) free wall Lagrangian strain was measured from the original coordinates. Within-twin pair ventricular strain differences including relationship to Quintero staging and response to laser therapy for TTTS were analyzed by Wilcoxon signed-rank test. The VVI strain measurements could be analyzed in 182 of 200 TTTS and 96 of 112 non-TTTS control ventricles. Within-pair strain was concordant in non-TTTS controls. Recipient LV strain was reduced at all Quintero stages compared with donors (P < .01). Recipient right ventricular strain was reduced only in stages 3 and 4 (P < .01). Strain improved at a median of 2 weeks following successful laser therapy. Intertwin differences in strain were independent of weight discordance. Recipient LV strain is reduced in stages 1 and 2 TTTS. Within-pair strain discordance may distinguish early TTTS from growth discordance and guide timing of and management following treatment. Copyright © 2013 Mosby, Inc. All rights reserved.

Twin pregnancy

DEFF Research Database (Denmark)

Sperling, Lene; Tabor, A

2001-01-01

Determination of chorionicity is one of the most important issues in the management of twin pregnancy. Modern ultrasound equipment has made it possible to accurately assess placentation already in the first trimester with the lambda sign. With regard to prenatal diagnosis, it is important to know...... for clinicians caring for twin pregnancies....

Tunable Superconducting Gravity Gradiometer for Mars Climate, Atmosphere, and Gravity Field Investigation

Science.gov (United States)

Griggs, C. E.; Paik, H. J.; Moody, M. V.; Han, S.-C.; Rowlands, D. D.; Lemoine, F. G.; Shirron, P. J.

2015-01-01

We are developing a compact tensor superconducting gravity gradiometer (SGG) for obtaining gravimetric measurements from planetary orbits. A new and innovative design gives a potential sensitivity of approximately 10(sup -4) E Hz(sup - 1/2)( 1 E = 10(sup -9 S(sup -2) in the measurement band up to 0.1 Hz (suitale for short wavelength static gravity) and of approximately 10(sup -4) E Hz(sup - 1/2) in the frequency band less than 1 mHz (for long wavelength time-variable gravity) from the same device with a baseline just over 10 cm. The measurement band and sensitiy can be optimally tuned in-flight during the mission by changing resonance frequencies, which allows meaurements of both static and time-variable gravity fields from the same mission. Significant advances in the technologies needed for space-based cryogenic instruments have been made in the last decade. In particular, the use of cryocoolers will alleviate the previously severe constraint on mission lifetime imposed by the use of liquid helium, enabling mission durations in the 5 - 10 year range.

Marital status and twins' health and behavior: an analysis of middle-aged Danish twins

DEFF Research Database (Denmark)

Osler, Merete; McGue, Matt; Lund, Rikke

2008-01-01

mass index (BMI), depression symptoms, self-rated health, cognitive function, physical activity, smoking, and alcohol intake. RESULTS: Among all 2350 individual twins, men who were divorced/widowed or never married had higher depression scores, lower cognitive test scores, lower physical activity....../widowed twin had higher average depression scores and was more likely to be a smoker. Never married twins had lower physical activity scores and never married male twins had higher BMI and higher depression scores than their married co-twin. CONCLUSION: This study suggests that the relationships of adult...... divorce with depression and smoking in Danish twins are due to the stressful effects of marital dissolution, but that marital differences in other health and behavioral outcomes are most consistent with selection effects related to genetic or rearing environmental factors....

Register-based research on twins

DEFF Research Database (Denmark)

Christensen, Kaare; Ohm Kyvik, Kirsten; Holm, Niels V

2011-01-01

Introduction: The Danish Twin Registry (DTR) has for more than 50 years been based on surveys and clinical investigations and over the two last decades also on register linkage. Currently these two approaches are merged within Statistics Denmark. Research topics: Here we report on three major...... groups of register-based research in the DTR that used the uniqueness of twinning. First, we focus on the ''long-term prognosis'' of being a twin compared with being a singleton and show that Danish twins have health trajectories in adulthood similar to singletons, which is a result of interest for twins...... illustrate how the co-twin control method in a register setting can be used to control for the effect of rearing environment and genetic factors in studies of the association between exposures and health. CONCLUSION: The spectrum of register-based twin studies is very wide and have changed in accordance...

High energy scattering in gravity and supergravity

DEFF Research Database (Denmark)

B. Giddings, Steven; Schmidt-Sommerfeld, Maximilian; Andersen, Jeppe Rosenkrantz

2010-01-01

We investigate features of perturbative gravity and supergravity by studying scattering in the ultraplanckian limit, and sharpen arguments that the dynamics is governed by long-distance physics. A simple example capturing aspects of the eikonal resummation suggests why short distance phenomena...... and in particular divergences or nonrenormalizability do not necessarily play a central role in this regime. A more profound problem is apparently unitarity. These considerations can be illustrated by showing that known gravity and supergravity amplitudes have the same long-distance behavior, despite the extra...... a physical scattering process, and ultraplanckian scattering exhibiting Regge behavior. These arguments sharpen the need to find a nonperturbative completion of gravity with mechanisms which restore unitarity in the strong gravity regime....

Quantum and gravity. Blend or melange?

Energy Technology Data Exchange (ETDEWEB)

Wuethrich, Christian [University of Geneva (Switzerland)

2016-07-01

Do we need to quantize gravity, as it is tacitly assumed in much of fundamental physics? The standard lore falls short of justifying an affirmative answer. Black hole thermodynamics is widely considered, faint though it may be, our firmest hint at a quantum theory of gravity - despite the failure to date to observe Hawking radiation or any other effect that would require going beyond a classical description of black holes. Hawking radiation hitherto merely enjoys a theoretical derivation in a semi-classical theory combining quantum matter with classical gravity. But how can a semi-classical melange of physical principles possibly justify that the quantum and gravity are blended into a unified fundamental theory when the latter is generally expected to reject at least some of the principles in the former?.

Birth size and gestational age in opposite-sex twins as compared to same-sex twins

DEFF Research Database (Denmark)

Jelenkovic, Aline; Sund, Reijo; Yokoyama, Yoshie

2018-01-01

It is well established that boys are born heavier and longer than girls, but it remains unclear whether birth size in twins is affected by the sex of their co-twin. We conducted an individual-based pooled analysis of 21 twin cohorts in 15 countries derived from the COllaborative project of Develo......It is well established that boys are born heavier and longer than girls, but it remains unclear whether birth size in twins is affected by the sex of their co-twin. We conducted an individual-based pooled analysis of 21 twin cohorts in 15 countries derived from the COllaborative project....... In girls, birth size was not associated (5 g birth weight; 95% CI -8 to -18 and -0.089 cm birth length; 95% CI -0.202 to 0.025) with the sex of the co-twin. Gestational age was slightly shorter in boy-boy pairs than in boy-girl and girl-girl pairs. When birth size was standardized by gestational age......, the magnitude of the associations was attenuated in boys, particularly for birth weight. In conclusion, boys with a co-twin sister are heavier and longer at birth than those with a co-twin brother. However, these differences are modest and partly explained by a longer gestation in the presence of a co...

Four-dimensional real-time sonographically guided cauterization of the umbilical cord in a case of twin-twin transfusion syndrome.

Science.gov (United States)

Timor-Tritsch, Ilan E; Rebarber, Andrei; MacKenzie, Andrew; Caglione, Christopher F; Young, Bruce K

2003-07-01

In the past decade, three-dimensional (3D) sonographic technology has matured from a static imaging modality to near-real-time imaging. One of the more notable improvements in this technology has been the speed with which the imaged volume is acquired and displayed. This has enabled the birth of the near-real-time or four-dimensional (4D) sonographic concept. Using the 4D feature of the current 3D sonography machines allows us to follow moving structures, such as fetal motion, in almost real time. Shortly after the emergence of 3D and 4D technology as a clinical imaging tool, its use in guiding needles into structures was explored by other investigators. We present a case in which we used the 4D feature of our sonographic equipment to follow the course and motion of an instrument inserted into the uterus to occlude the umbilical cord of a fetus in a case of twin-twin transfusion syndrome.

Fetal growth disorders in twin gestations.

LENUS (Irish Health Repository)

Breathnach, Fionnuala M

2012-06-01

Twin growth is frequently mismatched. This review serves to explore the pathophysiologic mechanisms that underlie growth aberrations in twin gestations, the prenatal recognition of abnormal twin growth, and the critical importance of stratifying management of abnormal twin growth by chorionicity. Although poor in utero growth of both twins may reflect maternal factors resulting in global uteroplacental dysfunction, discordant twin growth may be attributed to differences in genetic potential between co-twins, placental dysfunction confined to one placenta only, or one placental territory within a shared placenta. In addition, twin-twin transfusion syndrome represents a distinct entity of which discordant growth is a common feature. Discordant growth is recognized as an independent risk factor for adverse perinatal outcome. Intertwin birth weight disparity of 18% or more should be considered to represent a discordance threshold, which serves as an independent risk factor for adverse perinatal outcome. At this cutoff, perinatal morbidity is found to increase both for the larger and the smaller twin within a discordant pair. There remains uncertainty surrounding the sonographic parameters that are most predictive of discordance. Although heightening of fetal surveillance in the face of discordant twin growth follows the principles applied to singleton gestations complicated by fetal growth restriction, the timing of intervention is largely influenced by chorionicity.

Neonatal status of twins

Directory of Open Access Journals (Sweden)

Božinović Dragica

2012-01-01

Full Text Available Multiple pregnancy is a pregnancy where more than one fetus develops simultaneously in the womb, as a result of the ovulation and fertilization of more than one egg. It is relatively rare in humans and represents the rest of the phylogenetic stages. The most common are twins and they indicate the development of two fetuses in the womb. The frequency of twin pregnancies is about 1%. Multiple pregnancies belong to a group of high-risk pregnancies because of the many complications that occur during the pregnancy: higher number of premature deliveries, bleeding, early neonatal complications and higher perinatal morbidity and mortality. Such pregnancies and infants require greater supervision and monitoring. The aim of this study was to determine the percentage of baby twins born at the maternity ward of the General Hospital in Prokuplje and their morbidity and mortality. Data on the total number of deliveries, number of twins, parity and maternal age, gestational age, body weight of twins, method of delivery, Apgar score and perinatal mortality were collected and statistically analyzed by means of retrospective analysis of operative birth and neonatal protocol for 6 years (2005 of 2010. Out of 4527 mothers who gave birth 43 were pairs of twins, or 0.95% of women gave birth to twins. These babies are more likely born by Caesarean section, but delivered with slightly lower birth weight.

Losing one twin in the NICU - A case study of parental experience

DEFF Research Database (Denmark)

Aagaard, Hanne; Storm, Ida; Klitgaard, Jeannett

2016-01-01

and revealed tree overall themes. These themes indicate that besides struggling with grief related to the loss of one infant, the parents were challenged by the medical discourse, the lack of staff continuity and space to develop parenthood. This case study emphasizes how the loss of a premature twin......The aim of this case study was to generate a deeper understanding of parents’ experiences of losing one twin in the NICU. In an in-depth interview the parents told their story of giving birth to twins born extremely preterm and shortly after losing one of them. A thematic analysis was conducted...... reinforced the parents’ need of an understandable dialogue with a team of nurses. Furthermore the nurses have to offer a close partnership and create the necessary space for parents to develop parenthood while simultaneously dealing with the unexpected and traumatising circumstances related to the loss...

Cohort Profile : The National Academy of Sciences-National Research Council Twin Registry (NAS-NRC Twin Registry)

NARCIS (Netherlands)

Gatz, Margaret; Harris, Jennifer R.; Kaprio, Jaakko; McGue, Matt; Smith, Nicholas L.; Snieder, Harold; Spiro, Avron; Butler, David A.

The National Academy of Sciences-National Research Council Twin Registry (NAS-NRC Twin Registry) is a comprehensive registry of White male twin pairs born in the USA between 1917 and 1927, both of the twins having served in the military. The purpose was medical research and ultimately improved

Monozygotic twins with discordant intestinal rotation

International Nuclear Information System (INIS)

Smith, Vance L.; Nwomeh, Benedict C.; Long, Frederick

2006-01-01

Previous case reports have suggested a strong concordance of intestinal malrotation among identical twins. This has led to the recommendation that the asymptomatic twin undergo screening when malrotation is discovered in the identical sibling. We present a case of monozygotic twins in which one twin presented with intestinal malrotation with midgut volvulus while the other twin was found to have normal gastrointestinal anatomy. (orig.)

Monozygotic twins with discordant intestinal rotation

Energy Technology Data Exchange (ETDEWEB)

Smith, Vance L.; Nwomeh, Benedict C. [Ohio State University College of Medicine and Public Health, Department of Pediatric Surgery, Columbus Children' s Hospital, Columbus, OH (United States); Long, Frederick [Ohio State University College of Medicine and Public Health, Department of Radiology, Columbus Children' s Hospital, Columbus, OH (United States)

2006-04-15

Previous case reports have suggested a strong concordance of intestinal malrotation among identical twins. This has led to the recommendation that the asymptomatic twin undergo screening when malrotation is discovered in the identical sibling. We present a case of monozygotic twins in which one twin presented with intestinal malrotation with midgut volvulus while the other twin was found to have normal gastrointestinal anatomy. (orig.)

A Computational Discriminability Analysis on Twin Fingerprints

Science.gov (United States)

Liu, Yu; Srihari, Sargur N.

Sharing similar genetic traits makes the investigation of twins an important study in forensics and biometrics. Fingerprints are one of the most commonly found types of forensic evidence. The similarity between twins’ prints is critical establish to the reliability of fingerprint identification. We present a quantitative analysis of the discriminability of twin fingerprints on a new data set (227 pairs of identical twins and fraternal twins) recently collected from a twin population using both level 1 and level 2 features. Although the patterns of minutiae among twins are more similar than in the general population, the similarity of fingerprints of twins is significantly different from that between genuine prints of the same finger. Twins fingerprints are discriminable with a 1.5%~1.7% higher EER than non-twins. And identical twins can be distinguished by examine fingerprint with a slightly higher error rate than fraternal twins.

3p interstitial deletion including PRICKLE2 in identical twins with autistic features.

Science.gov (United States)

Okumura, Akihisa; Yamamoto, Toshiyuki; Miyajima, Masakazu; Shimojima, Keiko; Kondo, Satoshi; Abe, Shinpei; Ikeno, Mitsuru; Shimizu, Toshiaki

2014-11-01

Microdeletion and microduplication syndromes without characteristic dysmorphic features are difficult to diagnose without chromosomal microarrays. We describe the clinical course and genetic findings of monozygotic twins with intellectual disabilities and autistic features associated with mild facial dysmorphism and microdeletion of chromosome 3p14. The postnatal course of the second twin was complicated by intestinal malrotation, whereas that of the first twin was unremarkable. Both twins had several mild dysmorphic features including upswept frontal hair, low-set posterior rotated ears, arched down-slanting eyebrows, prominent forehead, epicanthic folds, micrognathia, hypertelorism, broad nasal bridge, short philtrum, and camptodactyly of the bilateral fifth fingers. They had autistic features such as poor eye contact and no social smile, stereotyped behaviors, and preference for solitary play. Array comparative genomic hybridization analysis revealed de novo 6.88-Mb deletions of 3p14 (chr3: 60,472,496-67,385,119) involving 17 genes in both twins. The deleted region contained 17 genes, five of which are known or presumed to be related to central nervous system disorders: FEZF2, SYNPR, ATXN7, PRICKLE2, and MAGI1. We consider that PRICKLE2 is the most likely causative gene for the autistic features exhibited by these individuals. Copyright © 2014 Elsevier Inc. All rights reserved.

The utility of twins in developmental cognitive neuroscience research: How twins strengthen the ABCD research design.

Science.gov (United States)

Iacono, William G; Heath, Andrew C; Hewitt, John K; Neale, Michael C; Banich, Marie T; Luciana, Monica M; Madden, Pamela A; Barch, Deanna M; Bjork, James M

2018-08-01

The ABCD twin study will elucidate the genetic and environmental contributions to a wide range of mental and physical health outcomes in children, including substance use, brain and behavioral development, and their interrelationship. Comparisons within and between monozygotic and dizygotic twin pairs, further powered by multiple assessments, provide information about genetic and environmental contributions to developmental associations, and enable stronger tests of causal hypotheses, than do comparisons involving unrelated children. Thus a sub-study of 800 pairs of same-sex twins was embedded within the overall Adolescent Brain and Cognitive Development (ABCD) design. The ABCD Twin Hub comprises four leading centers for twin research in Minnesota, Colorado, Virginia, and Missouri. Each site is enrolling 200 twin pairs, as well as singletons. The twins are recruited from registries of all twin births in each State during 2006-2008. Singletons at each site are recruited following the same school-based procedures as the rest of the ABCD study. This paper describes the background and rationale for the ABCD twin study, the ascertainment of twin pairs and implementation strategy at each site, and the details of the proposed analytic strategies to quantify genetic and environmental influences and test hypotheses critical to the aims of the ABCD study. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Conjoined (Siamese) Twins in Zambia

African Journals Online (AJOL)

year-old Zambian multiparous mother gave birth to a set of twins with two heads ... (symmetric or mirror image) but one twin attached with an incomplete foetus is known as hetropagtrs. (asymmetrical). Thoracopagus twins (joined at the chest).

Ferrobielastic twinning in irradiated quartz

International Nuclear Information System (INIS)

Shiau, S.M.

1986-01-01

Cultured quartz is usually free from electrical twinning; however, it may occur if the seed crystal is twinned or if undue applied forces are exerted on the crystal. Ferrobielastic twinning was studied optically (photoelastic effect) and electrically (piezoelectric effect). At room temperature, twins were perceptible at stresses of about 2.l5 x 10 8 N/m 2 , and crystals switched from their original states to the alternative twin states at stresses about 5.0 x 10 8 N/m 2 (called coercive stress). The decrease in coercive stress with increasing temperature was observed, and these coercive stresses become very low as temperatures reach to 300 0 C. The effects of irradiation on the twinning in quartz were also studied. The presence of defects produced by irradiation was utilized to pin the domain wall motion. Both neutrons and gamma rays were employed. The stress required to nucleate an appreciable volume of twins is about twice as high for irradiated crystals than for those unirradiated. This result demonstrated that the irradiated crystals can tolerate higher stresses. However, the coercive stress for complete switch-over was not much different for irradiated and unirradiated crystals. It appears that the defects caused by irradiation eliminate the initial twinning events but do not affect switch-over

Voice similarity in identical twins.

Science.gov (United States)

Van Gysel, W D; Vercammen, J; Debruyne, F

2001-01-01

If people are asked to discriminate visually the two individuals of a monozygotic twin (MT), they mostly get into trouble. Does this problem also exist when listening to twin voices? Twenty female and 10 male MT voices were randomly assembled with one "strange" voice to get voice trios. The listeners (10 female students in Speech and Language Pathology) were asked to label the twins (voices 1-2, 1-3 or 2-3) in two conditions: two standard sentences read aloud and a 2.5-second midsection of a sustained /a/. The proportion correctly labelled twins was for female voices 82% and 63% and for male voices 74% and 52% for the sentences and the sustained /a/ respectively, both being significantly greater than chance (33%). The acoustic analysis revealed a high intra-twin correlation for the speaking fundamental frequency (SFF) of the sentences and the fundamental frequency (F0) of the sustained /a/. So the voice pitch could have been a useful characteristic in the perceptual identification of the twins. We conclude that there is a greater perceptual resemblance between the voices of identical twins than between voices without genetic relationship. The identification however is not perfect. The voice pitch possibly contributes to the correct twin identifications.

Co-bedding in neonatal nursery for promoting growth and neurodevelopment in stable preterm twins.

Science.gov (United States)

Lai, Nai Ming; Foong, Siew Cheng; Foong, Wai Cheng; Tan, Kenneth

2016-04-14

The increased birth rate of twins during recent decades and the improved prognosis of preterm infants have resulted in the need to explore measures that could optimize their growth and neurodevelopmental outcomes. It has been postulated that co-bedding simulates twins' intrauterine experiences in which co-regulatory behaviors between them are observed. These behaviors are proposed to benefit twins by reducing their stress, which may promote growth and development. However, in practice, uncertainty surrounds the benefit-risk profile of co-bedding. We aimed to assess the effectiveness of co-bedding compared with separate (individual) care for stable preterm twins in the neonatal nursery in promoting growth and neurodevelopment and reducing short- and long-term morbidities, and to determine whether co-bedding is associated with significant adverse effects.As secondary objectives, we sought to evaluate effects of co-bedding via the following subgroup analyses: twin pairs with different weight ranges (very low birth weight [VLBW] growth discordance at birth, preterm versus borderline preterm twins, twins co-bedded in incubator versus cot at study entry, and twins randomized by twin pair versus neonatal unit. We used the standard search strategy of the Cochrane Neonatal Review Group (CNRG). We used keywords and medical subject headings (MeSH) to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 2), MEDLINE (via PubMed), EMBASE (hosted by EBSCOHOST), the Cumulative Index to Nursing and Allied Health Literature (CINAHL), and references cited in our short-listed articles, up to February 29, 2016. We included randomized controlled trials with randomization by twin pair and/or by neonatal unit. We excluded cross-over studies. We extracted data using standard methods of the CNRG. Two review authors independently assessed the relevance and risk of bias of retrieved records. We contacted the authors of included studies to request important

HIGH PRECISION ABUNDANCES OF THE OLD SOLAR TWIN HIP 102152: INSIGHTS ON Li DEPLETION FROM THE OLDEST SUN

Energy Technology Data Exchange (ETDEWEB)

Monroe, TalaWanda R.; Melendez, Jorge; Tucci Maia, Marcelo; Freitas, Fabricio C. [Departamento de Astronomia do IAG/USP, Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, 05508-900 Sao Paulo, SP (Brazil); Ramirez, Ivan [McDonald Observatory, The University of Texas at Austin, Austin, TX 78712 (United States); Yong, David; Asplund, Martin; Alves-Brito, Alan; Casagrande, Luca [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston, ACT 2611 (Australia); Bergemann, Maria [Max Planck Institute for Astrophysics, Postfach 1317, D-85741 Garching (Germany); Bedell, Megan; Bean, Jacob [Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Ave., Chicago, IL 60637 (United States); Lind, Karin [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Castro, Matthieu; Do Nascimento, Jose-Dias [Departamento de Fisica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Bazot, Michael, E-mail: tmonroe@usp.br [Centro de Astrofisica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal)

2013-09-10

We present the first detailed chemical abundance analysis of the old 8.2 Gyr solar twin, HIP 102152. We derive differential abundances of 21 elements relative to the Sun with precisions as high as 0.004 dex ({approx}<1%), using ultra high-resolution (R = 110,000), high S/N UVES spectra obtained on the 8.2 m Very Large Telescope. Our determined metallicity of HIP 102152 is [Fe/H] = -0.013 {+-} 0.004. The atmospheric parameters of the star were determined to be 54 K cooler than the Sun, 0.09 dex lower in surface gravity, and a microturbulence identical to our derived solar value. Elemental abundance ratios examined versus dust condensation temperature reveal a solar abundance pattern for this star, in contrast to most solar twins. The abundance pattern of HIP 102152 appears to be the most similar to solar of any known solar twin. Abundances of the younger, 2.9 Gyr solar twin, 18 Sco, were also determined from UVES spectra to serve as a comparison for HIP 102152. The solar chemical pattern of HIP 102152 makes it a potential candidate to host terrestrial planets, which is reinforced by the lack of giant planets in its terrestrial planet region. The following non-local thermodynamic equilibrium Li abundances were obtained for HIP 102152, 18 Sco, and the Sun: log {epsilon} (Li) = 0.48 {+-} 0.07, 1.62 {+-} 0.02, and 1.07 {+-} 0.02, respectively. The Li abundance of HIP 102152 is the lowest reported to date for a solar twin, and allows us to consider an emerging, tightly constrained Li-age trend for solar twin stars.

Growth curves for twins in Slovenia.

Science.gov (United States)

Bricelj, Katja; Blickstein, Isaac; Bržan-Šimenc, Gabrijela; Janša, Vid; Lučovnik, Miha; Verdenik, Ivan; Trojner-Bregar, Andreja; Tul, Nataša

2017-02-01

Abnormalities of fetal growth are more common in twins. We introduce the growth curves for monitoring fetal growth in twin pregnancies in Slovenia. Slovenian National Perinatal Information System for the period between 2002 and 2010 was used to calculate birth weight percentiles for all live born twins for each week from 22nd to 40th week. The calculated percentiles of birth weight for all live-born twins in Slovenia served as the basis for drawing 'growth' curves. The calculated growth curves for twins will help accurately diagnose small or large twin fetuses for their gestational age in the native central European population.

Deformation twinning: Influence of strain rate

Energy Technology Data Exchange (ETDEWEB)

Gray, G.T. III

1993-11-01

Twins in most crystal structures, including advanced materials such as intermetallics, form more readily as the temperature of deformation is decreased or the rate of deformation is increased. Both parameters lead to the suppression of thermally-activated dislocation processes which can result in stresses high enough to nucleate and grow deformation twins. Under high-strain rate or shock-loading/impact conditions deformation twinning is observed to be promoted even in high stacking fault energy FCC metals and alloys, composites, and ordered intermetallics which normally do not readily deform via twinning. Under such conditions and in particular under the extreme loading rates typical of shock wave deformation the competition between slip and deformation twinning can be examined in detail. In this paper, examples of deformation twinning in the intermetallics TiAl, Ti-48Al-lV and Ni{sub 3}A as well in the cermet Al-B{sub 4}C as a function of strain rate will be presented. Discussion includes: (1) the microstructural and experimental variables influencing twin formation in these systems and twinning topics related to high-strain-rate loading, (2) the high velocity of twin formation, and (3) the influence of deformation twinning on the constitutive response of advanced materials.

Apparition of iodinated contrast agents in twin neonatal gastrointestinal tracts after maternal contrast-enhanced computed tomography

International Nuclear Information System (INIS)

Kato, Hiroki; Kanematsu, Masayuki; Kato, Zenichiro; Kondo, Naomi; Orii, Kenji E.; Morimoto, Masahiro

2011-01-01

We describe a case of the appearance of iodinated contrast agents in the same locations of twins' neonatal gastrointestinal tracts 1 day after maternal contrast-enhanced computed tomography (CT). The CT examination had been performed on the expectant mother for suspected deep venous thrombosis on the day previous to the twin delivery. At 23 h after the CT examination and after cesarean section, iodinated contrast agents appeared in the same place in the twins' neonatal gastrointestinal tracts, mainly in the ascending colon, on plain abdominal radiographs. Radiologists, obstetricians, and pediatricians should understand the mechanism of appearance of iodinated contrast agents in fetal gastrointestinal tracts when the expectant mother had been given iodinated contrast agents intravenously shortly before delivery. (author)

Fingerprint recognition with identical twin fingerprints.

Science.gov (United States)

Tao, Xunqiang; Chen, Xinjian; Yang, Xin; Tian, Jie

2012-01-01

Fingerprint recognition with identical twins is a challenging task due to the closest genetics-based relationship existing in the identical twins. Several pioneers have analyzed the similarity between twins' fingerprints. In this work we continue to investigate the topic of the similarity of identical twin fingerprints. Our study was tested based on a large identical twin fingerprint database that contains 83 twin pairs, 4 fingers per individual and six impressions per finger: 3984 (83*2*4*6) images. Compared to the previous work, our contributions are summarized as follows: (1) Two state-of-the-art fingerprint identification methods: P071 and VeriFinger 6.1 were used, rather than one fingerprint identification method in previous studies. (2) Six impressions per finger were captured, rather than just one impression, which makes the genuine distribution of matching scores more realistic. (3) A larger sample (83 pairs) was collected. (4) A novel statistical analysis, which aims at showing the probability distribution of the fingerprint types for the corresponding fingers of identical twins which have same fingerprint type, has been conducted. (5) A novel analysis, which aims at showing which finger from identical twins has higher probability of having same fingerprint type, has been conducted. Our results showed that: (a) A state-of-the-art automatic fingerprint verification system can distinguish identical twins without drastic degradation in performance. (b) The chance that the fingerprints have the same type from identical twins is 0.7440, comparing to 0.3215 from non-identical twins. (c) For the corresponding fingers of identical twins which have same fingerprint type, the probability distribution of five major fingerprint types is similar to the probability distribution for all the fingers' fingerprint type. (d) For each of four fingers of identical twins, the probability of having same fingerprint type is similar.

Fingerprint recognition with identical twin fingerprints.

Directory of Open Access Journals (Sweden)

Xunqiang Tao

Full Text Available Fingerprint recognition with identical twins is a challenging task due to the closest genetics-based relationship existing in the identical twins. Several pioneers have analyzed the similarity between twins' fingerprints. In this work we continue to investigate the topic of the similarity of identical twin fingerprints. Our study was tested based on a large identical twin fingerprint database that contains 83 twin pairs, 4 fingers per individual and six impressions per finger: 3984 (83*2*4*6 images. Compared to the previous work, our contributions are summarized as follows: (1 Two state-of-the-art fingerprint identification methods: P071 and VeriFinger 6.1 were used, rather than one fingerprint identification method in previous studies. (2 Six impressions per finger were captured, rather than just one impression, which makes the genuine distribution of matching scores more realistic. (3 A larger sample (83 pairs was collected. (4 A novel statistical analysis, which aims at showing the probability distribution of the fingerprint types for the corresponding fingers of identical twins which have same fingerprint type, has been conducted. (5 A novel analysis, which aims at showing which finger from identical twins has higher probability of having same fingerprint type, has been conducted. Our results showed that: (a A state-of-the-art automatic fingerprint verification system can distinguish identical twins without drastic degradation in performance. (b The chance that the fingerprints have the same type from identical twins is 0.7440, comparing to 0.3215 from non-identical twins. (c For the corresponding fingers of identical twins which have same fingerprint type, the probability distribution of five major fingerprint types is similar to the probability distribution for all the fingers' fingerprint type. (d For each of four fingers of identical twins, the probability of having same fingerprint type is similar.

The classical twin study and beyond

NARCIS (Netherlands)

Boomsma, D.I.; Busjahn, A.; Peltonen, L.

2002-01-01

Twin studies have been a valuable source of information about the genetic basis of complex traits. To maximize the potential of twin studies, large, worldwide registers of data on twins and their relatives have been established. Here, we provide an overview of the current resources for twin

Prenatal diagnosis of monocephalic bifacial tetraophthalmic diprosopus (conjoined twin).

Science.gov (United States)

Dhaifalah, I; Curtisova, V; Santavy, J

2008-01-01

A case of diprosopus twinning which is rare conjoined twinning is reported prenatally at 22 weeks' gestation. 2D ultrasound examinations showed duplication of the craniofacial structures with four hemispheres, two cerebella and two thalami. There were three orbits two external ears, two noses, fused adjacent maxilla and two oral cavities with two fused oral opening and two jaws. The woman did not consent to any further investigations and the pregnancy was terminated. The postmortem examination confirmed the diagnosis in a male fetus with a crown-rump length of 155 mm, weighing 450 g. The body appeared normal except for a small poorly formed rudiment of a supernumerary digit next to the thumb of the right hand. The ultrasound examination and postmortem finding of this case is described with a short review of the literature. (c) 2007 S. Karger AG, Basel

Exotic quarks in Twin Higgs models

Energy Technology Data Exchange (ETDEWEB)

Cheng, Hsin-Chia [Department of Physics, University of California, Davis,One Shields Avenue, Davis, CA 95616 (United States); Jung, Sunghoon [School of Physics, Korea Institute for Advanced Study,85 Hoegiro, Dongdaemun-gu, Seoul 130-722 (Korea, Republic of); SLAC National Accelerator Laboratory,2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Salvioni, Ennio [Department of Physics, University of California, Davis,One Shields Avenue, Davis, CA 95616 (United States); Tsai, Yuhsin [Department of Physics, University of California, Davis,One Shields Avenue, Davis, CA 95616 (United States); Maryland Center for Fundamental Physics,Department of Physics, University of Maryland,College Park, MD 20742 (United States)

2016-03-14

The Twin Higgs model provides a natural theory for the electroweak symmetry breaking without the need of new particles carrying the standard model gauge charges below a few TeV. In the low energy theory, the only probe comes from the mixing of the Higgs fields in the standard model and twin sectors. However, an ultraviolet completion is required below ∼ 10 TeV to remove residual logarithmic divergences. In non-supersymmetric completions, new exotic fermions charged under both the standard model and twin gauge symmetries have to be present to accompany the top quark, thus providing a high energy probe of the model. Some of them carry standard model color, and may therefore be copiously produced at current or future hadron colliders. Once produced, these exotic quarks can decay into a top together with twin sector particles. If the twin sector particles escape the detection, we have the irreducible stop-like signals. On the other hand, some twin sector particles may decay back into the standard model particles with long lifetimes, giving spectacular displaced vertex signals in combination with the prompt top quarks. This happens in the Fraternal Twin Higgs scenario with typical parameters, and sometimes is even necessary for cosmological reasons. We study the potential displaced vertex signals from the decays of the twin bottomonia, twin glueballs, and twin leptons in the Fraternal Twin Higgs scenario. Depending on the details of the twin sector, the exotic quarks may be probed up to ∼ 2.5 TeV at the LHC and beyond 10 TeV at a future 100 TeV collider, providing a strong test of this class of ultraviolet completions.

Twin Anemia Polycythemia Sequence: Current Views on Pathogenesis, Diagnostic Criteria, Perinatal Management, and Outcome.

Science.gov (United States)

Tollenaar, Lisanne S A; Slaghekke, Femke; Middeldorp, Johanna M; Klumper, Frans J; Haak, Monique C; Oepkes, Dick; Lopriore, Enrico

2016-06-01

Monochorionic twins share a single placenta and are connected with each other through vascular anastomoses. Unbalanced inter-twin blood transfusion may lead to various complications, including twin-to-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS). TAPS was first described less than a decade ago, and the pathogenesis of TAPS results from slow blood transfusion from donor to recipient through a few minuscule vascular anastomoses. This gradually leads to anemia in the donor and polycythemia in the recipient, in the absence of twin oligo-polyhydramnios sequence (TOPS). TAPS may occur spontaneously in 3-5% of monochorionic twins or after laser surgery for TTTS. The prevalence of post-laser TAPS varies from 2% to 16% of TTTS cases, depending on the rate of residual anastomoses. Pre-natal diagnosis of TAPS is currently based on discordant measurements of the middle cerebral artery peak systolic velocity (MCA-PSV; >1.5 multiples of the median [MoM] in donors and 8 g/dL), and at least one of the following: reticulocyte count ratio >1.7 or minuscule placental anastomoses. Management includes expectant management, and intra-uterine blood transfusion (IUT) with or without partial exchange transfusion (PET) or fetoscopic laser surgery. Post-laser TAPS can be prevented by using the Solomon laser surgery technique. Short-term neonatal outcome ranges from isolated inter-twin Hb differences to severe neonatal morbidity and neonatal death. Long-term neonatal outcome in post-laser TAPS is comparable with long-term outcome after treated TTTS. This review summarizes the current knowledge after 10 years of research on the pathogenesis, diagnosis, management, and outcome in TAPS.

General relativity and gauge gravity theories of higher order

International Nuclear Information System (INIS)

Konopleva, N.P.

1998-01-01

It is a short review of today's gauge gravity theories and their relations with Einstein General Relativity. The conceptions of construction of the gauge gravity theories with higher derivatives are analyzed. GR is regarded as the gauge gravity theory corresponding to the choice of G ∞4 as the local gauge symmetry group and the symmetrical tensor of rank two g μν as the field variable. Using the mathematical technique, single for all fundamental interactions (namely variational formalism for infinite Lie groups), we can obtain Einstein's theory as the gauge theory without any changes. All other gauge approaches lead to non-Einstein theories of gravity. But above-mentioned mathematical technique permits us to construct the gauge gravity theory of higher order (for instance SO (3,1)-gravity) so that all vacuum solutions of Einstein equations are the solutions of the SO (3,1)-gravity theory. The structure of equations of SO(3,1)-gravity becomes analogous to Weeler-Misner geometrodynamics one

Twin Higgs Asymmetric Dark Matter.

Science.gov (United States)

García García, Isabel; Lasenby, Robert; March-Russell, John

2015-09-18

We study asymmetric dark matter (ADM) in the context of the minimal (fraternal) twin Higgs solution to the little hierarchy problem, with a twin sector with gauged SU(3)^{'}×SU(2)^{'}, a twin Higgs doublet, and only third-generation twin fermions. Naturalness requires the QCD^{'} scale Λ_{QCD}^{'}≃0.5-20  GeV, and that t^{'} is heavy. We focus on the light b^{'} quark regime, m_{b^{'}}≲Λ_{QCD}^{'}, where QCD^{'} is characterized by a single scale Λ_{QCD}^{'} with no light pions. A twin baryon number asymmetry leads to a successful dark matter (DM) candidate: the spin-3/2 twin baryon, Δ^{'}∼b^{'}b^{'}b^{'}, with a dynamically determined mass (∼5Λ_{QCD}^{'}) in the preferred range for the DM-to-baryon ratio Ω_{DM}/Ω_{baryon}≃5. Gauging the U(1)^{'} group leads to twin atoms (Δ^{'}-τ^{'}[over ¯] bound states) that are successful ADM candidates in significant regions of parameter space, sometimes with observable changes to DM halo properties. Direct detection signatures satisfy current bounds, at times modified by dark form factors.

Propagation of short-period gravity waves at high-latitudes during the MaCWAVE winter campaign

Directory of Open Access Journals (Sweden)

K. Nielsen

2006-07-01

Full Text Available As part of the MaCWAVE (Mountain and Convective Waves Ascending Vertically winter campaign an all-sky monochromatic CCD imager has been used to investigate the properties of short-period mesospheric gravity waves at high northern latitudes. Sequential measurements of several nightglow emissions were made from Esrange, Sweden, during a limited period from 27–31 January 2003. Coincident wind measurements over the altitude range (~80–100 km using two meteor radar systems located at Esrange and Andenes have been used to perform a novel investigation of the intrinsic properties of five distinct wave events observed during this period. Additional lidar and MSIS model temperature data have been used to investigate their nature (i.e. freely propagating or ducted. Four of these extensive wave events were found to be freely propagating with potential source regions to the north of Scandinavia. No evidence was found for strong orographic forcing by short-period waves in the airglow emission layers. The fifth event was most unusual exhibiting an extensive, but much smaller and variable wavelength pattern that appeared to be embedded in the background wind field. Coincident wind measurements indicated the presence of a strong shear suggesting this event was probably due to a large-scale Kelvin-Helmholtz instability.

Attachment to the Romantic Partner and Sibling: Attachment Hierarchies of Twins and Non-Twin Siblings

Directory of Open Access Journals (Sweden)

Sascha Schwarz

2015-12-01

Full Text Available Previous studies have shown that romantic partners and siblings are important attachment figures. This study compares the attachment to the romantic partner with the attachment to the sibling as a function of the participant’s sibling type among monozygotic (MZ twins, dizygotic (DZ twins, and non-twin (NT siblings. The results show that MZ twins prefer their sibling to their romantic partner whereas DZ twins are equally attached to their sibling and romantic partner. In contrast, NT siblings are more attached to their romantic partner compared to their sibling. These results indicate that genetic relatedness has profound impact on a person’s attachment hierarchy and the relative rank of the romantic partner and the sibling.

Low twinning rate and seasonal effects on twinning in a fertile population, the Hutterites

Science.gov (United States)

Nonaka, K.; Miura, T.; Peter, K.

1993-09-01

This paper analyzes from the mid 18th century to 1987 the birth records of the “Dariusleut,” one of the three subgroups of the Hutterite population. The aim of this study is to describe several aspects of the twinning rate in a fertile population. The overall rate of twinning was 0.90%:103 twins among all 11492 maternities. The rate peaked at the 7th birth order and at the maternal age of 40 years and over. Until the mid 19th century when the Hutterites lived in Russia, the twinning rate was higher (1.5%), and it decreased during the migration period in the second half of the 19th century (0.7%). After the group had settled in the USA and Canada, the population maintained a twinning rate of 1.0% until 1965. After 1965 the rate decreased to 0.7%, partly due to a decline in fertility among women aged 30 years and over. There was a significant seasonal variation: the twinning rate decreased to 0.5% in May July compared to 1.2% for the other three seasons during the years up to 1965 ( P<0.01), while more recent mothers did not show such a seasonal variation. The incidence of twin births in this population seems to have been influenced by environmental factors, which would change their effect seasonally and secularly.

Quantum gravity at a Lifshitz point

International Nuclear Information System (INIS)

Horava, Petr

2009-01-01

We present a candidate quantum field theory of gravity with dynamical critical exponent equal to z=3 in the UV. (As in condensed-matter systems, z measures the degree of anisotropy between space and time.) This theory, which at short distances describes interacting nonrelativistic gravitons, is power-counting renormalizable in 3+1 dimensions. When restricted to satisfy the condition of detailed balance, this theory is intimately related to topologically massive gravity in three dimensions, and the geometry of the Cotton tensor. At long distances, this theory flows naturally to the relativistic value z=1, and could therefore serve as a possible candidate for a UV completion of Einstein's general relativity or an infrared modification thereof. The effective speed of light, the Newton constant and the cosmological constant all emerge from relevant deformations of the deeply nonrelativistic z=3 theory at short distances.

Effects of artificial gravity on the cardiovascular system: Computational approach

Science.gov (United States)

Diaz Artiles, Ana; Heldt, Thomas; Young, Laurence R.

2016-09-01

Artificial gravity has been suggested as a multisystem countermeasure against the negative effects of weightlessness. However, many questions regarding the appropriate configuration are still unanswered, including optimal g-level, angular velocity, gravity gradient, and exercise protocol. Mathematical models can provide unique insight into these questions, particularly when experimental data is very expensive or difficult to obtain. In this research effort, a cardiovascular lumped-parameter model is developed to simulate the short-term transient hemodynamic response to artificial gravity exposure combined with ergometer exercise, using a bicycle mounted on a short-radius centrifuge. The model is thoroughly described and preliminary simulations are conducted to show the model capabilities and potential applications. The model consists of 21 compartments (including systemic circulation, pulmonary circulation, and a cardiac model), and it also includes the rapid cardiovascular control systems (arterial baroreflex and cardiopulmonary reflex). In addition, the pressure gradient resulting from short-radius centrifugation is captured in the model using hydrostatic pressure sources located at each compartment. The model also includes the cardiovascular effects resulting from exercise such as the muscle pump effect. An initial set of artificial gravity simulations were implemented using the Massachusetts Institute of Technology (MIT) Compact-Radius Centrifuge (CRC) configuration. Three centripetal acceleration (artificial gravity) levels were chosen: 1 g, 1.2 g, and 1.4 g, referenced to the subject's feet. Each simulation lasted 15.5 minutes and included a baseline period, the spin-up process, the ergometer exercise period (5 minutes of ergometer exercise at 30 W with a simulated pedal cadence of 60 RPM), and the spin-down process. Results showed that the cardiovascular model is able to predict the cardiovascular dynamics during gravity changes, as well as the expected

Education in Twins and Their Parents Across Birth Cohorts Over 100 years: An Individual-Level Pooled Analysis of 42-Twin Cohorts.

Science.gov (United States)

Silventoinen, Karri; Jelenkovic, Aline; Latvala, Antti; Sund, Reijo; Yokoyama, Yoshie; Ullemar, Vilhelmina; Almqvist, Catarina; Derom, Catherine A; Vlietinck, Robert F; Loos, Ruth J F; Kandler, Christian; Honda, Chika; Inui, Fujio; Iwatani, Yoshinori; Watanabe, Mikio; Rebato, Esther; Stazi, Maria A; Fagnani, Corrado; Brescianini, Sonia; Hur, Yoon-Mi; Jeong, Hoe-Uk; Cutler, Tessa L; Hopper, John L; Busjahn, Andreas; Saudino, Kimberly J; Ji, Fuling; Ning, Feng; Pang, Zengchang; Rose, Richard J; Koskenvuo, Markku; Heikkilä, Kauko; Cozen, Wendy; Hwang, Amie E; Mack, Thomas M; Siribaddana, Sisira H; Hotopf, Matthew; Sumathipala, Athula; Rijsdijk, Fruhling; Sung, Joohon; Kim, Jina; Lee, Jooyeon; Lee, Sooji; Nelson, Tracy L; Whitfield, Keith E; Tan, Qihua; Zhang, Dongfeng; Llewellyn, Clare H; Fisher, Abigail; Burt, S Alexandra; Klump, Kelly L; Knafo-Noam, Ariel; Mankuta, David; Abramson, Lior; Medland, Sarah E; Martin, Nicholas G; Montgomery, Grant W; Magnusson, Patrik K E; Pedersen, Nancy L; Dahl Aslan, Anna K; Corley, Robin P; Huibregtse, Brooke M; Öncel, Sevgi Y; Aliev, Fazil; Krueger, Robert F; McGue, Matt; Pahlen, Shandell; Willemsen, Gonneke; Bartels, Meike; van Beijsterveldt, Catharina E M; Silberg, Judy L; Eaves, Lindon J; Maes, Hermine H; Harris, Jennifer R; Brandt, Ingunn; Nilsen, Thomas S; Rasmussen, Finn; Tynelius, Per; Baker, Laura A; Tuvblad, Catherine; Ordoñana, Juan R; Sánchez-Romera, Juan F; Colodro-Conde, Lucia; Gatz, Margaret; Butler, David A; Lichtenstein, Paul; Goldberg, Jack H; Harden, K Paige; Tucker-Drob, Elliot M; Duncan, Glen E; Buchwald, Dedra; Tarnoki, Adam D; Tarnoki, David L; Franz, Carol E; Kremen, William S; Lyons, Michael J; Maia, José A; Freitas, Duarte L; Turkheimer, Eric; Sørensen, Thorkild I A; Boomsma, Dorret I; Kaprio, Jaakko

2017-10-01

Whether monozygotic (MZ) and dizygotic (DZ) twins differ from each other in a variety of phenotypes is important for genetic twin modeling and for inferences made from twin studies in general. We analyzed whether there were differences in individual, maternal and paternal education between MZ and DZ twins in a large pooled dataset. Information was gathered on individual education for 218,362 adult twins from 27 twin cohorts (53% females; 39% MZ twins), and on maternal and paternal education for 147,315 and 143,056 twins respectively, from 28 twin cohorts (52% females; 38% MZ twins). Together, we had information on individual or parental education from 42 twin cohorts representing 19 countries. The original education classifications were transformed to education years and analyzed using linear regression models. Overall, MZ males had 0.26 (95% CI [0.21, 0.31]) years and MZ females 0.17 (95% CI [0.12, 0.21]) years longer education than DZ twins. The zygosity difference became smaller in more recent birth cohorts for both males and females. Parental education was somewhat longer for fathers of DZ twins in cohorts born in 1990-1999 (0.16 years, 95% CI [0.08, 0.25]) and 2000 or later (0.11 years, 95% CI [0.00, 0.22]), compared with fathers of MZ twins. The results show that the years of both individual and parental education are largely similar in MZ and DZ twins. We suggest that the socio-economic differences between MZ and DZ twins are so small that inferences based upon genetic modeling of twin data are not affected.

A tale of twin Higgs: natural twin two Higgs doublet models

International Nuclear Information System (INIS)

Yu, Jiang-Hao

2016-01-01

In original twin Higgs model, vacuum misalignment between electroweak and new physics scales is realized by adding explicit ℤ 2 breaking term. Introducing additional twin Higgs could accommodate spontaneous ℤ 2 breaking, which explains origin of this misalignment. We introduce a class of twin two Higgs doublet models with most general scalar potential, and discuss general conditions which trigger electroweak and ℤ 2 symmetry breaking. Various scenarios on realising the vacuum misalignment are systematically discussed in a natural composite two Higgs double model framework: explicit ℤ 2 breaking, radiative ℤ 2 breaking, tadpole-induced ℤ 2 breaking, and quartic-induced ℤ 2 breaking. We investigate the Higgs mass spectra and Higgs phenomenology in these scenarios.

Using Twins to Better Understand Sibling Relationships.

Science.gov (United States)

Mark, Katharine M; Pike, Alison; Latham, Rachel M; Oliver, Bonamy R

2017-03-01

We compared the nature of the sibling relationship in dyads of varying genetic relatedness, employing a behavioural genetic design to estimate the contribution that genes and the environment have on this familial bond. Two samples were used-the Sisters and Brothers Study consisted of 173 families with two target non-twin children (mean ages = 7.42 and 5.22 years respectively); and the Twins, Family and Behaviour study included 234 families with two target twin children (mean age = 4.70 years). Mothers and fathers reported on their children's relationship with each other, via a postal questionnaire (the Sisters and Brothers Study) or a telephone interview (the Twins, Family and Behaviour study). Contrary to expectations, no mean level differences emerged when monozygotic twin pairs, dizygotic twin pairs, and non-twin pairs were compared on their sibling relationship quality. Behavioural genetic analyses also revealed that the sibling bond was modestly to moderately influenced by the genetic propensities of the children within the dyad, and moderately to substantially influenced by the shared environment common to both siblings. In addition, for sibling negativity, we found evidence of twin-specific environmental influence-dizygotic twins showed more reciprocity than did non-twins. Our findings have repercussions for the broader application of results from future twin-based investigations.

Incidence of spontaneous twin anemia-polycythemia sequence in monochorionic-diamniotic twin pregnancies: Single-center prospective study.

Science.gov (United States)

Yokouchi, Tae; Murakoshi, Takeshi; Mishima, Takashi; Yano, Hiroko; Ohashi, Madoka; Suzuki, Takashi; Shinno, Takashi; Matsushita, Mitsuru; Nakayama, Satoru; Torii, Yuichi

2015-06-01

The purpose of this study was to prospectively estimate the incidence of spontaneous twin anemia-polycythemia sequence (TAPS) in monochorionic-diamniotic twin pregnancies. We prospectively examined umbilical cord hemoglobin (Hb) and reticulocyte count of consecutive monochorionic-diamniotic twin pregnancies delivered at Seirei Hamamatsu General Hospital from December 2006 to September 2013. We excluded cases of twin-twin transfusion syndrome, intrauterine fetal demise, and missing data (Hb and reticulocyte count missing from the medical record). TAPS was diagnosed using the postnatal criteria of intertwin Hb difference >8.0 g/dL and reticulocyte count ratio >1.7. Acute feto-fetal hemorrhage was defined as Hb difference >7 g/dL and reticulocyte count ratio <1.7. A total of 185 monochorionic-diamniotic twin pregnancies were included in this study. Three fulfilled the diagnostic criteria for postnatal TAPS, and one fulfilled the diagnostic criteria for acute feto-fetal hemorrhage. The incidence of spontaneous TAPS in monochorionic-diamniotic twin pregnancies was 1.6% (3/185) at Seirei Hamamatsu General Hospital. © 2014 The Authors. Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology.

SUSY meets her twin

Energy Technology Data Exchange (ETDEWEB)

Katz, Andrey [Theory Division, CERN,CH-1211 Geneva 23 (Switzerland); Département de Physique Théorique and Center for Astroparticle Physics (CAP),Université de Genève,24 quai Ansermet, CH-1211 Genève 4 (Switzerland); Mariotti, Alberto [Theoretische Natuurkunde and IIHE/ELEM, Vrije Universiteit Brussel,and International Solvay Institutes,Pleinlaan 2, B-1050 Brussels (Belgium); Pokorski, Stefan [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw,ul. Pasteura 5, PL-02-093 Warsaw (Poland); Redigolo, Diego [Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University,Tel-Aviv 69978 (Israel); Department of Particle Physics and Astrophysics, Weizmann Institute of Science,Rehovot 7610001 (Israel); Ziegler, Robert [Institute for Theoretical Particle Physics (TTP), Karlsruhe Institute of Technology,Engesserstraße 7, D-76128 Karlsruhe (Germany)

2017-01-31

We investigate the general structure of mirror symmetry breaking in the Twin Higgs scenario. We show, using the IR effective theory, that a significant gain in fine tuning can be achieved if the symmetry is broken hardly. We emphasize that weakly coupled UV completions can naturally accommodate this scenario. We analyze SUSY UV completions and present a simple Twin SUSY model with a tuning of around 10% and colored superpartners as heavy as 2 TeV. The collider signatures of general Twin SUSY models are discussed with a focus on the extended Higgs sectors.

From monster to twin reversed arterial perfusion: a history of acardiac twins.

Science.gov (United States)

Obladen, Michael

2010-05-01

A human being born without heart and head, i.e., the acardius/acranius malformation, has been described since antiquity. Superstition and fear made it a mystical disorder, a sign of God's wrath. The inquisition ruled that acranic infants should not be baptized and located the soul in the brain. Acardia was not associated with twin gestation until the reports of Mery in 1720 and Winslow in 1740. In 1850, Meckel identified the pathogenetic mechanism as reversed perfusion due to large arterio-arterial and veno-venous anastomoses; he believed the heart would fail to develop or arrest during development, and the acardiac fetus would be maintained by arterial perfusion from the pump twin. In 1859, Claudius articulated that after normal initial development, the heart degenerates when reversed flow in the aorta leads to thrombosis. Today, it is assumed that both mechanisms may exist. With the advent of prenatal ultrasound diagnosis and radiofrequency ablation of the acardiac twin's circulation, it became possible to save the pump twin.

Monochorionic twin pregnancies: a systematic approach to ...

African Journals Online (AJOL)

Complications unique to these pregnancies include Twin-To-Twin Transfusion Syndrome (TTTS), Twin Polycythaemia Anaemia Sequence (TAPS), Selective Intrauterine Growth Restriction (sIUGR) and death of the co-twin. Adhering to a systematic and objective approach of management, can lead to early recognition and ...

Cesarean Section for the Second Twin

DEFF Research Database (Denmark)

Engelbrechtsen, Line; Nielsen, Elise Hoffmann; Perin, Trine

2013-01-01

deliveries. Data were extracted from medical records, a fetal medicine software program (Astraia), and the National Birth Registry. Short-term poor neonatal outcome was measured as a 5-minute Apgar score ≤ 7, umbilical cord pH ≤ 7.10, and admission to neonatal intensive care unit for more than 3 days....... RESULTS: Vertex-nonvertex fetal presentations were more prevalent in combined deliveries than vaginal deliveries (OR 4.4, 2.5-7.8). Nonvertex second twins born by combined delivery had a higher risk of Apgar score ≤ 7 and umbilical cord pH ≤ 7.10 compared with vaginal delivery, unadjusted OR 6.2 (2...

Assessing GOCE Gravity Models using Altimetry and In-situ Ocean Current Observation

DEFF Research Database (Denmark)

Knudsen, Per; Andersen, Ole Baltazar; Honecker, Johanna

gravity models provided by the GOCE mission have enhanced the resolution and sharpened the boundaries of those features and the associated geostrophic surface currents reveal improvements for all of the ocean's current systems. In this study, a series of 23 newer gravity models including observations from...... as quantified quality measures associated with the 23 GOCE gravity models.......The Gravity and steady state Ocean Circulation Explorer (GOCE) satellite mission measures Earth's gravity field with an unprecedented accuracy at short spatial scales. Previous results have demonstrated a significant advance in our ability to determine the ocean's general circulation. The improved...

A tale of twin Higgs: natural twin two Higgs doublet models

Energy Technology Data Exchange (ETDEWEB)

Yu, Jiang-Hao [Amherst Center for Fundamental Interactions, Department of Physics,University of Massachusetts Amherst,710 North Pleasant St., Amherst, MA 01002 (United States)

2016-12-28

In original twin Higgs model, vacuum misalignment between electroweak and new physics scales is realized by adding explicit ℤ{sub 2} breaking term. Introducing additional twin Higgs could accommodate spontaneous ℤ{sub 2} breaking, which explains origin of this misalignment. We introduce a class of twin two Higgs doublet models with most general scalar potential, and discuss general conditions which trigger electroweak and ℤ{sub 2} symmetry breaking. Various scenarios on realising the vacuum misalignment are systematically discussed in a natural composite two Higgs double model framework: explicit ℤ{sub 2} breaking, radiative ℤ{sub 2} breaking, tadpole-induced ℤ{sub 2} breaking, and quartic-induced ℤ{sub 2} breaking. We investigate the Higgs mass spectra and Higgs phenomenology in these scenarios.

Massive gravity from bimetric gravity

International Nuclear Information System (INIS)

Baccetti, Valentina; Martín-Moruno, Prado; Visser, Matt

2013-01-01

We discuss the subtle relationship between massive gravity and bimetric gravity, focusing particularly on the manner in which massive gravity may be viewed as a suitable limit of bimetric gravity. The limiting procedure is more delicate than currently appreciated. Specifically, this limiting procedure should not unnecessarily constrain the background metric, which must be externally specified by the theory of massive gravity itself. The fact that in bimetric theories one always has two sets of metric equations of motion continues to have an effect even in the massive gravity limit, leading to additional constraints besides the one set of equations of motion naively expected. Thus, since solutions of bimetric gravity in the limit of vanishing kinetic term are also solutions of massive gravity, but the contrary statement is not necessarily true, there is no complete continuity in the parameter space of the theory. In particular, we study the massive cosmological solutions which are continuous in the parameter space, showing that many interesting cosmologies belong to this class. (paper)

Establishing a Twin Registry in Guinea-Bissau

DEFF Research Database (Denmark)

Bjerregaard-Andersen, Morten; Gomes, Margarida A; Joaquím, Luis C

2013-01-01

represent a powerful tool. Though twin studies have been carried out by the Bandim Health Project for more than 30 years, the renewed registry described here was officially established in 2009 and includes both a cohort of newborn twins and a cohort of young and adult twins. Currently more than 1,500 twins...

Anorexia and bulimia nervosa in same-sex and opposite-sex twins: lack of association with twin type in a nationwide study of Finnish twins.

Science.gov (United States)

Raevuori, Anu; Kaprio, Jaakko; Hoek, Hans W; Sihvola, Elina; Rissanen, Aila; Keski-Rahkonen, Anna

2008-12-01

The authors tested the hypothesis that either prenatal feminization or masculinization hormone influences in utero or later socialization affects the risk for anorexia and bulimia nervosa and disordered eating in members of opposite-sex twin pairs. Finnish twins (N=2,426 women, N=1,962 men with known zygosity) from birth cohorts born 1974-1979 were assessed at age 22 to 28 years with a questionnaire for eating disorder symptoms. Based on the questionnaire screen, women (N=292), men (N=53), and their cotwins were interviewed to assess diagnoses of anorexia nervosa and bulimia nervosa (per DSM-IV and broad criteria). In women from opposite-sex twin pairs, the prevalence of DSM-IV or broad anorexia nervosa was not significantly different than that of women from monozygotic pairs or same-sex dizygotic pairs. Of the five male anorexia nervosa probands, only one was from an opposite-sex twin pair. Bulimia nervosa in men was too rare to be assessed by zygosity; the prevalence of DSM-IV or broad bulimia nervosa did not differ in women from opposite- versus same-sex twin pairs. In both sexes, the overall profile of indicators on eating disorders was rather similar between individuals from opposite- and same-sex pairs. The authors found little evidence that the risk for anorexia nervosa, bulimia nervosa, or disordered eating was associated with zygosity or sex composition of twin pairs, thus making it unlikely that in utero femininization or masculinization or socialization effects of growing up with an opposite-sex twin have a major influence on the later development of eating disorders.

Heteropagus twinning on back -- a case report.

Science.gov (United States)

Debnath, Bidyut; Biswas, Sumitra Kumar

2011-07-01

Heteropagus twins, also called parasitic twins, are malformation of the foetus where the development of one twin is incomplete. They are attached most commonly to the lower chest and upper abdomen. We report a case of heteropagus twin, where the parasite possessed well-formed limb as well as blind ending intestine. It was attached to the back of the host by a broad pedicle. We take this opportunity to classify areas of confusion prevailing regarding twinning, foetus in foetu, teratoma and caudal duplication.

High-Resolution Gravity Field Modeling for Mercury to Estimate Crust and Lithospheric Properties

Science.gov (United States)

Goossens, S.; Mazarico, E.; Genova, A.; James, P. B.

2018-05-01

We estimate a gravity field model for Mercury using line-of-sight data to improve the gravity field model at short wavelengths. This can be used to infer crustal density and infer the support mechanism of the lithosphere.

Time trends in the natural dizygotic twinning rate.

Science.gov (United States)

Derom, Catherine; Gielen, Marij; Peeters, Hilde; Frijns, Jean-Pierre; Zeegers, Maurice P A

2011-08-01

The natural dizygotic (DZ) twinning rate has been proposed as a reliable and useful measure of human fecundity, if adjusted for maternal age at twin birth. The aim of this study was to analyze age-adjusted trends in natural DZ twinning rates over the past 40 years using data from the 'East Flanders Prospective Twin Survey (EFPTS)'. This study involved 4835 naturally conceived twin pregnancies between 1969 and 2009 from the population-based Belgian 'EFPTS'. Age-adjusted trends in the incidence of natural DZ twin pregnancies were calculated using a generalized linear model with Poisson distribution. Both the natural DZ twinning rates and maternal age at twin birth increased in a linear fashion from 1969 to 2009. When age-adjusted, we found that the trend in the natural DZ twinning rate was stable during the whole time period. According to our population-based data and after age-adjustment, a stable natural DZ twinning rate could be observed over the last four decades. Under the assumption that the spontaneous DZ twinning rate is a sensor of fecundity, this indicates a stable 'high' fecundity for this population.

Relationship between refractive error and ocular biometrics in twin children: the Guangzhou Twin Eye Study.

Science.gov (United States)

Wang, Decai; Liu, Bin; Huang, Shengsong; Huang, Wenyong; He, Mingguang

2014-09-01

A cross-sectional study was conducted to explore the relationship between refractive error and ocular biometrics in children from the Guangzhou twin eye study. Twin participants aged 7-15 years were selected from Guangzhou Twin Eye Study. Ocular examinations included visual acuity measurement, ocular motility evaluation, autorefraction under cycloplegia, and anterior segment, media, and fundus examination. Axial length (AL), anterior chamber depth (ACD), and corneal curvature radius were measured using partial coherence laser interferometry. A multivariate linear regression model was used for statistical analysis. Twin children from Guangzhou city showed a decreased spherical equivalent with age, whereas both AL and ACD were increased and corneal curvature radius remained unchanged. When adjusted by age and gender, the data from 77% of twins presenting with spherical equivalent changes indicated that these were caused by predictable variables (R2 = 0.77, P biometrics. Refractive status is largely determined by axial length as the major factor.

Twins with omphalocele in Denmark (1970-1989)

DEFF Research Database (Denmark)

Bugge, Merete

2010-01-01

Seven pairs of twins, two monozygotic (MZ), two dizygotic (DZ), and three like-sex pairs of unknown zygosity are described. The twin pairs were all discordant for omphalocele except for one pair of conjoined twins. The 8 infants with omphalocele represent 3.1% of the 253 infants with omphalocele......, ascertained in an almost complete nationwide data set of live- and stillborn infants with abdominal wall defects in two decades in Denmark (1970-1989). The occurrence of twins with omphalocele was not significantly different from the occurrence of twins in the Danish population in the same period. To our...... knowledge this is the first report of the occurrence of twins with omphalocele in a systematic nationwide epidemiological study....

Twin anemia polycythemia sequence

NARCIS (Netherlands)

Slaghekke, Femke

2014-01-01

In this thesis we describe that Twin Anemia Polycythemia Sequence (TAPS) is a form of chronic feto-fetal transfusion in monochorionic (identical) twins based on a small amount of blood transfusion through very small anastomoses. For the antenatal diagnosis of TAPS, Middle Cerebral Artery – Peak

The Danish Twin Registry

DEFF Research Database (Denmark)

Skytthe, Axel; Ohm Kyvik, Kirsten; Vilstrup Holm, Niels

2011-01-01

Introduction: The Danish Twin Registry is a unique source for studies of genetic, familial and environmental factors on life events, health conditions and diseases. Content: More than 85,000 twin pairs born 1870-2008 in Denmark. Validity and coverage: Four main ascertainment methods have been emp...

Nature versus nurture: identical twins and bariatric surgery.

Science.gov (United States)

Hagedorn, Judith C; Morton, John M

2007-06-01

Genetics and environment both play a role in weight maintenance. Twin studies may help clarify the influence of nature vs nurture in weight loss. We present the largest U.S. experience with monozygotic (MZ) twins undergoing bariatric surgery. We retrospectively reviewed the charts of four sets of MZ twins who underwent Roux-en-Y gastric bypass (RYGBP) surgery and laparoscopic adjustable gastric band (LAGB) placement at three different institutions. BMI and co-morbidities were examined pre- and postoperatively, and laboratory values were recorded. All four sets of twins are female, live together, and have similar professions. Twin cohort 1 had near identical weight loss patterns after open RYGBP surgery in 1996 (preop 146/142 kg; 2 years 82/82; and 10 years 108/107). Twin cohort 1 also both underwent cholecystectomies within the first year postoperatively. Twin cohort 2 underwent laparoscopic RYGBP surgery and also required cholecystectomies in the first postoperative year. Cohort 2 also experienced nearly identical weight loss at 1 year (36.7% vs 37.0% BMI loss). Twin cohort 3 underwent LAGB placement with two different surgeons with differing amounts of weight loss at 6 months (6.5% vs 15.7% BMI loss). Finally, twin cohort 4 underwent laparoscopic RYGBP with 2-year BMI loss of 39% vs 34%. In twin cohort 4, the twin who lost less weight lived apart from her twin and extended family, and her weight loss was less than the twin living with her family. Two sets of MZ twins had identical responses to bariatric surgery. The other two sets of identical twins had differential weight loss results, possibly due to differences in surgical approach and social support. While genetics do exert a strong influence on weight loss and maintenance, this case series demonstrates the potential effect of social support and postoperative management upon postoperative weight loss in the presence of identical genetics.

Illustrations of the twin paradox

International Nuclear Information System (INIS)

Rebhan, E.

1985-01-01

In order to provide a more intuitive understanding of the twin paradox, several illustrations of this are presented. In one of these, each of the twins is equipped with a lamp whose monochromatic light can be observed by the other. In other illustrations the travelling twin uses an Einstein train instead of a space ship, all the cars of the train and all stations along the route of the train being equipped with clocks. (author)

Twins in Ancient Greece: a synopsis.

Science.gov (United States)

Malamitsi-Puchner, Ariadne

2016-01-01

This brief outline associates twins with several aspects of life in Ancient Greece. In Greek mythology twins caused ambivalent reactions and were believed to have ambivalent feelings for each other. Very often, they were viewed as the representatives of the dualistic nature of the universe. Heteropaternal superfecundation, which dominates in ancient myths, explains on one hand, the god-like qualities and, on the other hand, the mortal nature of many twins. An assumption is presented that legends referring to twins might reflect the territorial expansions of Ancient Greeks in Northern Mediterranean, around the Black Sea, in Asia Minor, as well as North East Africa. In conclusion, in Greek antiquity, twins have been used as transitional figures between myth and reality.

Twin birth order, birthweight and birthweight discordance: any relationship

Directory of Open Access Journals (Sweden)

Onyiriuka A.N.

2010-12-01

Full Text Available Background: It is widely believed that in twin pairs, at birth, the first-born weigh more than the second-born but this concept has been challenged. Objective: To assess the truthfulness of this common concept that first-born twins are usually heavier than their second-born siblings at birth. Methods: In a series of 104 sets of live-born twins, the birth weights of first-born twins were compared with those of their second-born siblings, after controlling for gender. Their intra-pair birthweight differences were determined and twin pairs whose birthweight difference was 15% or more were designated as discordant. Results: Twin I was heavier than Twin II in 61.5% of cases while Twin II was heavier than Twin I in 28.9% of cases. Twins I and II had equal birthweights in 9.6% of cases. Comparing the mean birthweight of the first-born-male twin with that of second-born- male twin, it was 2515+427g (95% Confidence Interval, CI=2402-2628 versus 2432 +435g (95% CI=2321-2543 p>0.05. The mean birthweight of first-born-female twin was 2326+445g (95% CI=2214-2439 while that of the second-born-female twin was 2325+501g (95% CI=2197-2453 p>0.05. When the birthweight difference exceeded 750g, the probability that Twin I will be heavier than Twin II was 83.3% (5 of 6. Conclusion: Although the first-born twin was more often heavier than their second-born siblings, either could weigh more or less at birth. The larger the birthweight difference between growth-discordant twin pair, the greater the probability that the heavier twin would be delivered first

Association between the birth of twins and parental divorce.

Science.gov (United States)

Jena, Anupam B; Goldman, Dana P; Joyce, Geoffrey

2011-04-01

Mothers of multiple births face higher rates of postpartum depression, yet evidence on the marital consequences of multiple births is limited. We examined the association between twin births and parental divorce. We used the 1980 U.S. Census to identify a large sample of mothers with and without twin births. The goal was to estimate multivariate logistic models of the association between birth of twins and divorce adjusting for race, age at marriage and first birth, and college education. We examined whether the association was affected by maternal education, age and sex composition of twins, and family size. Twins at first birth were associated with greater parental divorce compared with singletons (odds ratio, 1.08; 95% confidence interval, 1.01-1.16; absolute risk 13.7% with twins compared with 12.7%; P=.02). The association was statistically greater among mothers not attending college (14.9% with twins compared with 13.3%; P=.01) compared with those with some college (10.4% with twins compared with 10.5%; P=.34); those with children older than 8 years (15.6% with twins compared with 13.5%; P<.01) compared with younger children (10.6% with twins compared with 10.8%; P=.42); and those with at least one twin girl (13.8% with twins compared with 12.6%; P=.03) compared with twin boys (12.1% with twins compared with 12.5%, P=.38). Mothers with four or more children had a larger association between birth of twins and divorce (15.4% for mothers with twins at fourth birth compared with 11.3% for all other mothers with four or more children; P<.01) compared with mothers with twins at first birth (13.7% for twins at first birth compared with 12.7%; P=.02). Health consequences of twin births for children and mothers are well known. Twin births may be associated with longer-term parental divorce. Specific groups, namely mothers not completing college and mothers who already have more children, may be at higher risk. II.

A de novo Mutation in KMT2A (MLL) in monozygotic twins with Wiedemann-Steiner syndrome.

Science.gov (United States)

Dunkerton, Sophie; Field, Matthew; Cho, Vicki; Bertram, Edward; Whittle, Belinda; Groves, Alexandra; Goel, Himanshu

2015-09-01

Growth deficiency, psychomotor delay, and facial dysmorphism was originally described in a male patient in 1989 by Wiedemann et al. and later in 2000 by Steiner et al. Wiedemann-Steiner syndrome (WSS) has since been described only a few times in the literature, with the phenotypic spectrum both expanding and becoming more delineated with each patient reported. We report on the clinical and molecular features of monozygotic twins with a de novo mutation in KMT2A. Single nucleotide polymorphism (SNP) microarray was done on both twins and whole-exome sequencing was done using both parents and one of the affected twins. SNP microarray confirmed that they were monozygotic twins. A de novo heterozygous variant (p. Arg1083*) in the KMT2A gene was identified through whole-exome sequencing, confirming the diagnosis of WSS. In this study, we have identified a de novo mutation in KMT2A associated with psychomotor developmental delay, facial dysmorphism, short stature, hypertrichosis cubiti, and small kidneys. This finding in monozygotic twins gives specificity to the WSS. The description of more cases of WSS is needed for further delineation of this condition. Small kidneys with normal function have not been described in this condition in the medical literature before. © 2015 Wiley Periodicals, Inc.

The Role of Grain Orientation and Grain Boundary Characteristics in the Mechanical Twinning Formation in a High Manganese Twinning-Induced Plasticity Steel

Science.gov (United States)

Shterner, Vadim; Timokhina, Ilana B.; Rollett, Anthony D.; Beladi, Hossein

2018-04-01

In the current study, the dependence of mechanical twinning on grain orientation and grain boundary characteristics was investigated using quasi in-situ tensile testing. The grains of three main orientations (i.e., , , and parallel to the tensile axis (TA)) and certain characteristics of grain boundaries (i.e., the misorientation angle and the inclination angle between the grain boundary plane normal and the TA) were examined. Among the different orientations, and were the most and the least favored orientations for the formation of mechanical twins, respectively. The orientation was intermediate for twinning. The annealing twin boundaries appeared to be the most favorable grain boundaries for the nucleation of mechanical twinning. No dependence was found for the inclination angle of annealing twin boundaries, but the orientation of grains on either side of the annealing twin boundary exhibited a pronounced effect on the propensity for mechanical twinning. Annealing twin boundaries adjacent to high Taylor factor grains exhibited a pronounced tendency for twinning regardless of their inclination angle. In general, grain orientation has a significant influence on twinning on a specific grain boundary.

Do MZ twins have discordant experiences of friendship? A qualitative hypothesis-generating MZ twin differences study

Science.gov (United States)

Moran, Nicola; Plomin, Robert

2017-01-01

Using a qualitative monozygotic (MZ) twin differences design we explored whether adolescent MZ twins report discordant peer relationships and, if so, whether they perceive them as causes, consequences or correlates of discordant behaviour. We gathered free-response questionnaire data from 497 families and conducted in-depth telephone interviews with 97 of them. Within this dataset n = 112 families (23% of the sample) described discordant peer relationships. Six categories of discordance were identified (peer victimisation, peer rejection, fewer friends, different friends, different attitudes to friendship and dependence on co-twin). Participants described peer relationship discordance arising as a result of chance occurrences, enhanced vulnerability in one twin or discordant behaviour. Consequences of discordant peer relationships were seen as discordance in self-confidence, future plans, social isolation, mental health and interests. In all cases the twin with worse peer experiences was seen as having a worse outcome. Specific hypotheses are presented. PMID:28727730

Testicular cancer in twins: a meta-analysis.

Science.gov (United States)

Neale, R E; Carrière, P; Murphy, M F G; Baade, P D

2008-01-15

In a meta-analysis of testicular cancer in twins, twins had a 30% increased risk (estimate 1.31, 95% CI 1.1-1.6), providing indirect support for the hypothesis that in utero hormone variations influence risk of testicular cancer. The summary-estimate for dizygotic twins was 1.3 (1.0-1.7) and for monozygotic or same sex twins 1.4 (1.2-1.8).

The Mid-Atlantic Twin Registry, revisited.

Science.gov (United States)

Lilley, Emily C H; Silberg, Judy L

2013-02-01

The Mid-Atlantic Twin Registry (MATR) is a population-based registry of more than 56,000 twins primarily born or living in Virginia, North Carolina, and South Carolina. The MATR employs several methods of ascertaining twins, and devotes considerable resources to tracking and maintaining communication with MATR participants. Researchers may utilize the MATR for administration of research services including study recruitment, collection of DNA, archival data set creation, as well as data collection through mailed, phone, or online surveys. In addition, the MATR houses the MATR Repository, with over 1,200 blood samples available for researchers interested in DNA genotyping. For over 35 years MATR twins have participated in research studies with investigators from diverse scientific disciplines and various institutions. These studies, which have resulted in numerous publications, have covered a range of topics, including the human microbiome, developmental psychopathology, depression, anxiety, substance use, epigenetics of aging, children of twins, pre-term birth, social attitudes, seizures, eating disorders, as well as sleep homeostasis. Researchers interested in utilizing twins are encouraged to contact the MATR to discuss potential research opportunities.

Prosocial and self-interested intra-twin pair behavior in monozygotic and dizygotic twins in the early to middle childhood transition.

Science.gov (United States)

Yirmiya, Karen; Segal, Nancy L; Bloch, Guy; Knafo-Noam, Ariel

2018-04-06

Several related and complementary theoretical frameworks have been proposed to explain the existence of prosocial behavior, despite its potential fitness cost to the individual. These include kin selection theory, proposing that organisms have a propensity to help those to whom they are genetically related, and reciprocity, referring to the benefit of being prosocial, depending on past and future mutual interactions. A useful paradigm to examine prosociality is to compare mean levels of this behavior between monozygotic (MZ) and dizygotic (DZ) twins. Here, we examined the performance of 883 6.5-year-old twins (139 MZ and 302 DZ same-sex 6.5-year-old full twin pairs) in the Differential Productivity Task. In this task, the twins' behaviors were observed under two conditions: working for themselves vs. working for their co-twin. There were no significant differences between the performances of MZ and DZ twins in the prosocial condition of the task. Correlations within the twin dyads were significantly higher in MZ than DZ twins in the self-interested condition. However, similar MZ and DZ correlations were found in the prosocial condition, supporting the role of reciprocity in twins' prosociality towards each other. © 2018 John Wiley & Sons Ltd.

Chronic central serous choroidopathy with severe visual loss in hyperopic microphthalmic identical twins

Directory of Open Access Journals (Sweden)

Fabry, Annelies

2011-01-01

Full Text Available Objective: To report chronic central serous choroidopathy with severe visual loss in hyperopic microphthalmic identical twins. Methods: The index patient was first examined in 1994, at age 31, and has been followed up closely for 17 years. He had repeated fluorescein and indocyanine green angiograms, OCT, ultrasound biometry, and recently also autofluorescence and EDI OCT. His twin brother was first examined in 2010, at age 47, and had a similar extensive exploration. Results: The index patient had a mean refractive error of +6 D OU and VA was 20/32++ in the RE and 20/200 in the LE in 1994. Vision slowly went down to 20/800+ in the RE and 20/600 in the LE in 2011. His twin brother has a mean refractive error of +6 D OU and VA 20/400 OU. Both have a short axial length of the eye, a thick choroid with dilated vessels, and central serous choroidopathy with cystic degeneration of the macula and retina in the posterior pole. Conclusions: We add to the reported complications of microphthalmos, chronic central serous choroidopathy.

Centrifuges for Microgravity Simulation. The Reduced Gravity Paradigm

International Nuclear Information System (INIS)

Loon, Jack J. W. A. van

2016-01-01

Due to the cumbersome nature of performing real microgravity—spaceflight research scientists have been searching for alternatives to perform simulated microgravity or partial gravity experiments on Earth. For more than a century one uses the slow rotating clinostat as developed by von Sachs at the end of the nineteenth century. Since then, the fast rotating clinostat, the 3D clinostat or the random positioning machine, the rotating wall vessels, tail suspension and bed rest head down tilt and lately the levitating magnets have been introduced. Several of these simulation systems provide some similarities of the responses and phenotypes as seen in real microgravity experiments. However, one should always realize that we cannot reduce gravity on Earth, other than the relative short duration free fall studies in e.g., drop towers or parabolic aircraft. In this paper we want to explore the possibility to apply centrifuges to simulate microgravity or maybe better to simulate hypo-gravity. This Reduced Gravity Paradigm, RGP is based on the premise that adaptations seen going from a hypergravity level to a lower gravity are similar as changes seen going from unit gravity to microgravity.

Centrifuges for Microgravity Simulation. The Reduced Gravity Paradigm

Energy Technology Data Exchange (ETDEWEB)

Loon, Jack J. W. A. van, E-mail: j.vanloon@vumc.nl [Department of Oral and Maxillofacial Surgery / Oral Pathology, Dutch Experiment Support Center, VU University Medical Center and Academic Centre for Dentistry Amsterdam, Amsterdam (Netherlands); TEC-MMG LIS Lab, European Space Agency Technology Center, Noordwijk (Netherlands)

2016-07-19

Due to the cumbersome nature of performing real microgravity—spaceflight research scientists have been searching for alternatives to perform simulated microgravity or partial gravity experiments on Earth. For more than a century one uses the slow rotating clinostat as developed by von Sachs at the end of the nineteenth century. Since then, the fast rotating clinostat, the 3D clinostat or the random positioning machine, the rotating wall vessels, tail suspension and bed rest head down tilt and lately the levitating magnets have been introduced. Several of these simulation systems provide some similarities of the responses and phenotypes as seen in real microgravity experiments. However, one should always realize that we cannot reduce gravity on Earth, other than the relative short duration free fall studies in e.g., drop towers or parabolic aircraft. In this paper we want to explore the possibility to apply centrifuges to simulate microgravity or maybe better to simulate hypo-gravity. This Reduced Gravity Paradigm, RGP is based on the premise that adaptations seen going from a hypergravity level to a lower gravity are similar as changes seen going from unit gravity to microgravity.

Intercomparison of AIRS and HIRDLS stratospheric gravity wave observations

Science.gov (United States)

Meyer, Catrin I.; Ern, Manfred; Hoffmann, Lars; Trinh, Quang Thai; Alexander, M. Joan

2018-01-01

We investigate stratospheric gravity wave observations by the Atmospheric InfraRed Sounder (AIRS) aboard NASA's Aqua satellite and the High Resolution Dynamics Limb Sounder (HIRDLS) aboard NASA's Aura satellite. AIRS operational temperature retrievals are typically not used for studies of gravity waves, because their vertical and horizontal resolution is rather limited. This study uses data of a high-resolution retrieval which provides stratospheric temperature profiles for each individual satellite footprint. Therefore the horizontal sampling of the high-resolution retrieval is 9 times better than that of the operational retrieval. HIRDLS provides 2-D spectral information of observed gravity waves in terms of along-track and vertical wavelengths. AIRS as a nadir sounder is more sensitive to short-horizontal-wavelength gravity waves, and HIRDLS as a limb sounder is more sensitive to short-vertical-wavelength gravity waves. Therefore HIRDLS is ideally suited to complement AIRS observations. A calculated momentum flux factor indicates that the waves seen by AIRS contribute significantly to momentum flux, even if the AIRS temperature variance may be small compared to HIRDLS. The stratospheric wave structures observed by AIRS and HIRDLS often agree very well. Case studies of a mountain wave event and a non-orographic wave event demonstrate that the observed phase structures of AIRS and HIRDLS are also similar. AIRS has a coarser vertical resolution, which results in an attenuation of the amplitude and coarser vertical wavelengths than for HIRDLS. However, AIRS has a much higher horizontal resolution, and the propagation direction of the waves can be clearly identified in geographical maps. The horizontal orientation of the phase fronts can be deduced from AIRS 3-D temperature fields. This is a restricting factor for gravity wave analyses of limb measurements. Additionally, temperature variances with respect to stratospheric gravity wave activity are compared on a

Intercomparison of AIRS and HIRDLS stratospheric gravity wave observations

Directory of Open Access Journals (Sweden)

C. I. Meyer

2018-01-01

Full Text Available We investigate stratospheric gravity wave observations by the Atmospheric InfraRed Sounder (AIRS aboard NASA's Aqua satellite and the High Resolution Dynamics Limb Sounder (HIRDLS aboard NASA's Aura satellite. AIRS operational temperature retrievals are typically not used for studies of gravity waves, because their vertical and horizontal resolution is rather limited. This study uses data of a high-resolution retrieval which provides stratospheric temperature profiles for each individual satellite footprint. Therefore the horizontal sampling of the high-resolution retrieval is 9 times better than that of the operational retrieval. HIRDLS provides 2-D spectral information of observed gravity waves in terms of along-track and vertical wavelengths. AIRS as a nadir sounder is more sensitive to short-horizontal-wavelength gravity waves, and HIRDLS as a limb sounder is more sensitive to short-vertical-wavelength gravity waves. Therefore HIRDLS is ideally suited to complement AIRS observations. A calculated momentum flux factor indicates that the waves seen by AIRS contribute significantly to momentum flux, even if the AIRS temperature variance may be small compared to HIRDLS. The stratospheric wave structures observed by AIRS and HIRDLS often agree very well. Case studies of a mountain wave event and a non-orographic wave event demonstrate that the observed phase structures of AIRS and HIRDLS are also similar. AIRS has a coarser vertical resolution, which results in an attenuation of the amplitude and coarser vertical wavelengths than for HIRDLS. However, AIRS has a much higher horizontal resolution, and the propagation direction of the waves can be clearly identified in geographical maps. The horizontal orientation of the phase fronts can be deduced from AIRS 3-D temperature fields. This is a restricting factor for gravity wave analyses of limb measurements. Additionally, temperature variances with respect to stratospheric gravity wave activity are

Clinical Factors Associated With Presentation Change of the Second Twin After Vaginal Delivery of the First Twin.

Science.gov (United States)

Panelli, Danielle M; Easter, Sarah Rae; Bibbo, Carolina; Robinson, Julian N; Carusi, Daniela A

2017-11-01

To identify clinical factors associated with a change from vertex to nonvertex presentation in the second twin after vaginal birth of the first. We assembled a retrospective cohort of women with viable vertex-vertex twin pregnancies who delivered the presenting twin vaginally. Women whose second twin changed from vertex to nonvertex after vaginal birth of the first were classified as experiencing an intrapartum change in presentation. Characteristics associated with intrapartum presentation change in a univariate analysis with a P value ≤.10 were then evaluated in a multivariate logistic regression model. Four-hundred fifty women met inclusion criteria, of whom 55 (12%) had intrapartum presentation change of the second twin. Women experiencing intrapartum presentation change were more likely to be multiparous (69% compared with 47%, Ppresentation of the second twin between the most recent antepartum ultrasonogram and the ultrasonogram done on admission to labor and delivery (11% compared with 4%, P=.04). In an adjusted analysis, multiparity and gestational age less than 34 weeks were significantly associated with presentation change (adjusted odds ratio [OR] 2.9, 95% CI 1.5-5.6 and adjusted OR 2.6, 95% CI 1.1-5.9, respectively). Women with intrapartum presentation change were more likely to undergo cesarean delivery for their second twin (44% compared with 7%, Ppresentation. Twenty of the 24 (83%) cesarean deliveries performed in the intrapartum presentation change group were done for issues related to malpresentation. Multiparity and gestational age less than 34 weeks are associated with intrapartum presentation change of the second twin.

Deformation twinning in irradiated ferritic/martensitic steels

Science.gov (United States)

Wang, K.; Dai, Y.; Spätig, P.

2018-04-01

Two different ferritic/martensitic steels were tensile tested to gain insight into the mechanisms of embrittlement induced by the combined effects of displacement damage and helium after proton/neutron irradiation in SINQ, the Swiss spallation neutron source. The irradiation conditions were in the range: 15.8-19.8 dpa (displacement per atom) with 1370-1750 appm He at 245-300 °C. All the samples fractured in brittle mode with intergranular or cleavage fracture surfaces when tested at room temperature (RT) or 300 °C. After tensile test, transmission electron microscopy (TEM) was employed to investigate the deformation microstructures. TEM-lamella samples were extracted directly below the intergranular fracture surfaces or cleavage surfaces by using the focused ion beam technique. Deformation twinning was observed in irradiated specimens at high irradiation dose. Only twins with {112} plane were observed in all of the samples. The average thickness of twins is about 40 nm. Twins initiated at the fracture surface, became gradually thinner with distance away from the fracture surface and finally stopped in the matrix. Novel features such as twin-precipitate interactions, twin-grain boundary and/or twin-lath boundary interactions were observed. Twinning bands were seen to be arrested by grain boundaries or large precipitates, but could penetrate martensitic lath boundaries. Unlike the case of defect free channels, small defect-clusters, dislocation loops and dense small helium bubbles were observed inside twins.

Roentgeno-cephalometric analysis on the twin

Energy Technology Data Exchange (ETDEWEB)

Choi, Hi Sup; Ahn, Hyung Kyu [College of Dentistry, Seoul National University, Seoul (Korea, Republic of)

1972-11-15

The purpose of this investigation can be sought for studying varients between twin by the cephalometric roentgenog raphic technics. The author have applied Down's, Bjork and Sakamoto's technic and measured in various angulations and length of cephalometric points. The results are as follows; 1. No significantly different data were found between twin. 2. There was no differences between normality and twin.

Twin-twin transfusion syndrome: cerebral ischemia is not the only fetal MR imaging finding

Energy Technology Data Exchange (ETDEWEB)

Kline-Fath, Beth M. [University of Cincinnati Medical Center, Department of Radiology, Cincinnati Children' s Hospital Medical Center, Cincinnati, OH (United States); Cincinnati Children' s Hospital, Department of Radiology, Cincinnati, OH (United States); Calvo-Garcia, Maria A.; O' Hara, Sara M.; Racadio, Judy M. [University of Cincinnati Medical Center, Department of Radiology, Cincinnati Children' s Hospital Medical Center, Cincinnati, OH (United States); Crombleholme, Timothy M. [University of Cincinnati Medical Center, Department of Surgery, Cincinnati Children' s Hospital Medical Center, Cincinnati, OH (United States)

2007-01-15

Twin-twin transfusion syndrome (TTTS) is a complication of monochorionic/diamniotic twin pregnancies. An imbalance of blood flow occurs through placental anastomoses, causing potentially significant morbidity and mortality in both twins. Although the sonographic findings of TTTS are well documented, we believe that MR imaging is a valuable adjunct. We describe the fetal MR imaging findings associated with TTTS. From 2003 to 2005, 37 consecutive MR imaging studies were performed on multiple-gestation pregnancies. Of the 37, 25 were consistent with TTTS, correlated and confirmed by sonographic criteria. MR fetal abnormalities were documented. Cerebral ischemia, which could not be demonstrated by sonography, was delineated well by MR imaging. New findings noted on fetal MR imaging were enlargement of cerebral venous sinuses in both twins, dilatation of the renal collecting system in the recipient, lung lesions in the recipient and cerebral malformations in the donor. MR imaging is an important adjunct in TTTS imaging. Its benefit over sonography is its clear definition of cerebral pathology, which is important for intervention and counseling. The new findings, particularly in the urinary tract and cerebral venous sinuses, also help support the diagnosis of TTTS and might reveal additional consequences of the altered hemodynamics that occur in TTTS. (orig.)

Twin-twin transfusion syndrome: cerebral ischemia is not the only fetal MR imaging finding

International Nuclear Information System (INIS)

Kline-Fath, Beth M.; Calvo-Garcia, Maria A.; O'Hara, Sara M.; Racadio, Judy M.; Crombleholme, Timothy M.

2007-01-01

Twin-twin transfusion syndrome (TTTS) is a complication of monochorionic/diamniotic twin pregnancies. An imbalance of blood flow occurs through placental anastomoses, causing potentially significant morbidity and mortality in both twins. Although the sonographic findings of TTTS are well documented, we believe that MR imaging is a valuable adjunct. We describe the fetal MR imaging findings associated with TTTS. From 2003 to 2005, 37 consecutive MR imaging studies were performed on multiple-gestation pregnancies. Of the 37, 25 were consistent with TTTS, correlated and confirmed by sonographic criteria. MR fetal abnormalities were documented. Cerebral ischemia, which could not be demonstrated by sonography, was delineated well by MR imaging. New findings noted on fetal MR imaging were enlargement of cerebral venous sinuses in both twins, dilatation of the renal collecting system in the recipient, lung lesions in the recipient and cerebral malformations in the donor. MR imaging is an important adjunct in TTTS imaging. Its benefit over sonography is its clear definition of cerebral pathology, which is important for intervention and counseling. The new findings, particularly in the urinary tract and cerebral venous sinuses, also help support the diagnosis of TTTS and might reveal additional consequences of the altered hemodynamics that occur in TTTS. (orig.)

Non-random X chromosome inactivation in an affected twin in a monozygotic twin pair discordant for Wiedemann-Beckwith syndrome

Energy Technology Data Exchange (ETDEWEB)

Oestavik, R.E.; Eiklid, K.; Oerstavik, K.H. [Ulleval Univ. Hospital, Oslo (Norway)] [and others

1995-03-27

Wiedemann-Beckwith syndrome (WBS) is a syndrome including exomphalos, macroglossia, and generalized overgrowth. The locus has been assigned to 11p15, and genomic imprinting may play a part in the expression of one or more genes involved. Most cases are sporadic. An excess of female monozygotic twins discordant for WBS have been reported, and it has been proposed that this excess could be related to the process of X chromosome inactivation. We have therefore studied X chromosome inactivation in 13-year-old monozygotic twin girls who were discordant for WBS. In addition, both twins had Tourette syndrome. The twins were monochorionic and therefore the result of a late twinning process. This has also been the case in previously reported discordant twin pairs with information on placentation. X chromosome inactivation was determined in DNA from peripheral blood cells by PCR analysis at the androgen receptor locus. The affected twin had a completely skewed X inactivation, where the paternal allele was on the active X chromosome in all cells. The unaffected twin had a moderately skewed X inactivation in the same direction, whereas the mother had a random pattern. Further studies are necessary to establish a possible association between the expression of WBS and X chromosome inactivation. 18 refs., 2 figs., 1 tab.

Urticaria in monozygotic and dizygotic twins

DEFF Research Database (Denmark)

Thomsen, Simon Francis; van der Sluis, Sophie; Kyvik, Kirsten Ohm

2012-01-01

Aim. To identify risk factors for urticaria, to determine the relative proportion of the susceptibility to urticaria that is due to genetic factors in an adult clinical twin sample, and to further determine whether the genetic susceptibility to urticaria overlaps with the genetic susceptibility...... to atopic diseases. Methods. A total of 256 complete twin pairs and 63 single twins, who were selected from sibships with self-reported asthma via a questionnaire survey of 21,162 adult twins from the Danish Twin Registry, were clinically interviewed about a history of urticaria and examined for atopic...... diseases. Data were analysed with Cox proportional hazards regression and variance components models. Results. A total of 151 individuals (26%) had a history of urticaria, whereas 24 (4%) had had symptoms within the past year. Female sex, HR = 2.09 (1.46-2.99), P = 0.000; hay fever, HR = 1.92 (1...

Twin pregnancy possibly associated with high semen quality

DEFF Research Database (Denmark)

Asklund, Camilla; Jensen, Tina Kold; Jørgensen, Niels

2007-01-01

BACKGROUND: Recent studies found an association between a long waiting time to pregnancy (TTP) and reduced probability of twinning and a reduced dizygotic (DZ) twinning rate in subfertile men. However, it remains unsolved whether semen quality is associated with twin offspring. We therefore studied...... the semen quality in a group of fathers of naturally conceived twins. METHODS: In this study, 37 fathers of DZ twins and 15 fathers of monozygotic (MZ) twins participated, and 349 normal fertile men served as a reference group. All men delivered a semen sample, underwent a physical examination and completed...... points higher than the reference group (P semen quality than the reference group, which supports...

Bilateral Norrie's disease in identical twins.

OpenAIRE

Sukumaran, K

1991-01-01

A case of Norrie's disease in an identical twins is reported. No positive family history was obtained. The couple had no other children. The older of the twins died at the age of 9 months of uncertain cause. To the best of my knowledge this is the first case of Norrie's disease reported in Malaysia. And its occurrence in an identical twins is very rare.

Dental twinning anomalies: the nomenclature enigma.

Science.gov (United States)

Killian, C M; Croll, T P

1990-07-01

Dental twinning results from abnormal events in the embryologic development of teeth. This paper describes the impossibility of assigning precise diagnostic terms, such as germination, fusion, macrodontia, and concrescence, to dental twinning anomalies because the entire course of odontogenesis cannot be witnessed. Traditional nomenclature is reviewed and seven cases that exemplify the principle are presented. Modification of nomenclature to describe dental twinning defects is suggested.

Problem in twin pregnancy: Findings of prenatal sonography and autopsy

International Nuclear Information System (INIS)

Kim, Jeong Ah; Cho, Jeong Yeon; Song, Mi Jin; Min, Jee Yeon; Lee, Young Ho; Lee, Hak Jong; Chun, Yi Kyeong; Kim, Yee Jeong; Hong, Sung Ran

2001-01-01

Multifetal gestations are high risk pregnancies with higher perinatal morbidity and mortality. Multifetal gestations are subject to unique complications including conjoined twins, twin-to-twin transfusion syndrome (TTTS), acardiac twins, twin embization of co-twin demise and heterotopic pregnancies. Prenatal sonographic diagnosis of types and complications of multifetal gestations is important for antenatal care and prediction of fetal outcome. This study was performed to present the prenatal ultrasonographic findings and pathologic findings of the unique complications of twin pregnancy. Acardia is a lethal anomaly occurring in 1% of monozygotic twin. The acardiac twin has a parasitic existence and depends on the donor (pump) twin for its blood supply via placental anastomoses and retrograde perfusion of umbilical cord. This twin reversed arterial perfusion (TRAP) sequence is a most extreme manifestation on the TTTS. Doppler verification reversed flow in umbilical cord of the acardiac twin confirms the diagnosis.

Anencephaly with incomplete twinning (diprosopus).

Science.gov (United States)

Riccardi, V M; Bergmann, C A

1977-10-01

A case of diprosopus with anencephaly is presented. It is suggested that such concurrence of neural tube defects and incomplete twinning corroborates the notion that a single pathogenetic mechanism may be common to both neural tube defects and monozygotic twinning.

Effects of Hypolimnetic Oxygenation on Mercury Cycling in Twin Lake, Washington

Science.gov (United States)

Beutel, M.; Dent, S.; Reed, B.; Moore, B.; Yonge, D.; Shallenberger, E.

2010-12-01

The accumulation of mercury in freshwater aquatic food webs is a widespread health concern. Nearly one-third of US lakes have fish consumption advisories in place due to elevated concentrations of mercury in fish tissue. Mercury, primarily from fossil fuel combustion, is widely deposited across the landscape in the form of ionic mercury. The deposited ionic mercury can be transformed to toxic methylmercury by anaerobic bacteria in anoxic waters and sediments. Once produced, methylmercury is taken up by algae and seston, and then biomagnified up the aquatic food web with levels increasing in successive trophic levels. This presentation summarizes three years (2008-2010) of mercury monitoring at North and South Twin Lakes, moderately deep (maximum depth ~15 m) meso-eutrophic lakes located on the Colville Indian Reservation in eastern Washington State. The objective of the study was to evaluate spatial and temporal patterns of the total and methyl mercury in the water column and zooplankton before and after the implementation of hypolimnetic oxygenation in North Twin Lake in 2009. The working hypothesis was that maintenance of an oxic hypolimnion would repress methylmercury enrichment in bottom waters, and subsequent uptake into zooplankton. Initial results confirm that oxygenation repressed hypolimnetic enrichment of methylmercury. In 2008, prior to oxygenation, peak levels of methylmercury in anaerobic bottom waters of North and South Twin Lakes were 0.4-0.6 ng/L. In 2009 levels were less than 0.05 ng/L in oxygenated North Twin Lake, but were again elevated in anaerobic bottom waters of South Twin Lake. Interestingly, during a two-week oxygenation test in North Twin Lake in the fall of 2008, bottom waters exhibited a short-term and reversible loss of methylmercury that correlated with a decrease in dissolved iron and manganese. Regarding zooplankton, total mercury was higher in zooplankton from oxygenated North Twin Lake relative to non-oxygenated South Twin Lake

Anorexia and Bulimia Nervosa in Same-Sex and Opposite-Sex Twins : Lack of Association With Twin Type in a Nationwide Study of Finnish Twins

NARCIS (Netherlands)

Raevuori, Anu; Kaprio, Jaakko; Hoek, Hans W.; Sihvola, Elina; Rissanen, Aila; Keski-Rahkonen, Anna

2008-01-01

Objective: The authors tested the hypothesis that either prenatal feminization or masculinization hormone influences in utero or later socialization affects the risk for anorexia and bulimia nervosa and disordered eating in members of opposite-sex twin pairs. Method: Finnish twins (N=2,426 women,

Neurological impairment in a surviving twin following intrauterine fetal demise of the co-twin: a case study.

Science.gov (United States)

Forrester, K R; Keegan, K M; Schmidt, J W

2013-01-01

It has been established that twin pregnancies are at an increased risk for complications, including the risk of morbidity or mortality for one or both of the infants. Cerebral palsy and other associated neurological deficits also occur at higher rates in twin pregnancies. This report examines two cases of intrauterine demise of one twin with subsequent survival of the co-twin. In both cases, the surviving infant suffered significant neurological sequelae. Impairments observed in these two cases include multicystic encephalomalacia and periventricular leukomalacia as well as the subsequent development of cerebral palsy. This case study explores the predisposing factors, incidence, pathophysiology, consequences, and future research implications of these findings.

Hypertensive disorders in twin pregnancy

NARCIS (Netherlands)

J.G. Santema (Job); E. Koppelaar (Elin); H.C.S. Wallenburg (Henk)

1995-01-01

textabstractObjective: To compare the incidence and severity of pregnancy-induced hypertensive disorders in twin pregnancy and in singleton gestation. Study design: Case-control study in the setting of a University Hospital. Each pregnancy of a consecutive series of 187 twin pregnancies attending

Twin-twin transfusion syndrome: neurodevelopment of infants treated with laser surgery

Directory of Open Access Journals (Sweden)

Denise Campos

2016-04-01

Full Text Available ABSTRACT Objective To assess the neurodevelopmental functions of survivors of twin-twin transfusion syndrome (TTTS treated by fetoscopic laser coagulation (FLC, during the first year of life, comparing them to a control group; and to verify the influence of specific variables on neurodevelopment. Method This was a prospective, longitudinal study. The sample comprised 33 monochorionic diamniotic twins who underwent FLC for treatment of TTTS and 22 full-term infants of single-fetus pregnancies. Bayley Scales of Infant and Toddler Development Screening Test were used for evaluation. Prenatal, perinatal and postnatal information were obtained. Results There was an increased frequency of infants in the TTTS group with inadequate performance compared to the control group. The identified variables (fetal donor, low economic income and cardiorespiratory disease negatively impacted expressive communication and fine motor skills. Conclusion Although through follow-up is recommended in all TTTS survivors, particular attention is required for the high-risk group as defined in this study.

Concordance for multiple sclerosis in Danish twins

DEFF Research Database (Denmark)

Hansen, T; Skytthe, Axel; Stenager, Egon

2005-01-01

The occurrence of multiple sclerosis (MS) in twins has not previously been studied in complete nationwide data sets. The existence of almost complete MS and twin registries in Denmark ensures that essentially unbiased samples of MS cases among twins can be obtained. In this population-based study...

Numerical Simulation of Twin Nozzle Injectors

OpenAIRE

Milak, Dino

2015-01-01

Fuel injectors for marine applications have traditionally utilized nozzles with symmetric equispaced orifice configuration. But in light of the new marine emission legislations the twin nozzle concept has arisen. The twin nozzle differs from the conventional configuration by utilizing two closely spaced orifices to substitute each orifice in the conventional nozzle. Injector manufacturers regard twin nozzle injectors as a promising approach to facilitate stable spray patterns independent of t...

Socio-psycho-historical observation on the twin. Sampling methods and case study of the atomic bomb exposed twins

Energy Technology Data Exchange (ETDEWEB)

Watanabe, S; Satow, Y; Ueoka, Hiroshi; Munaka, M; Kurihara, M [Hiroshima Univ. (Japan). Research Inst. for Nuclear Medicine and Biology

1980-07-01

The so-called ''twin control study'', mainly on the monozygotic twins one of which was A-bomb exposed and the other was non-exposed were carried out. Sampling was conducted utilizing the materials as follows: 1) The survey on casualities of A-bomb exposed families in Hiroshima which was undertaken in 1946. 2) The survey of A-bomb survivors in 1965. 3) A-bomb exposed family survey conducted between 1973 to 1975. 4) Investigations of A-bomb victims exposed in the proximal areas from the hypocenter. From the above mentioned materials 470 pairs were selected, of which 220 were exposed. Among them 172 pairs were twins of the same sex. Female and male pair were also employed. In one case they were exposed, while the others were nonexposed. Two pairs were examined under the following methods: 1) Depth interview to ascertain familial casualities with reference to the family life cycle. 2) Socio-historical research. 3) Motoaki's Jinkaku Shindan Kensa (Modified Rorschach test by H. Motoaki), and T.A.T. test. Results obtained were summarized as follows: 1) Both pairs of twins were of similar appearance and personality traits, and had a strong feeling of companionship for each other. 2) In family relationships, the persons studied were very conscious of the role expectations of elder and younger siblings in the twin pairs. 3) Through depth interviews and projective tests, A-bomb exposed pairs still showed deep psychological stresses, resulting from the A-bomb disaster. 4) Both among the exposed twins and within the nonexposed control group twin siblings had a close feeling of companionship for each other. However, nonexposed twins could not understand the psychological experience of twins who had been subjected to the atomic disaster.

Twinning of Polymer Crystals Suppressed by Entropy

Directory of Open Access Journals (Sweden)

Nikos Ch. Karayiannis

2014-09-01

Full Text Available We propose an entropic argument as partial explanation of the observed scarcity of twinned structures in crystalline samples of synthetic organic polymeric materials. Polymeric molecules possess a much larger number of conformational degrees of freedom than low molecular weight substances. The preferred conformations of polymer chains in the bulk of a single crystal are often incompatible with the conformations imposed by the symmetry of a growth twin, both at the composition surfaces and in the twin axis. We calculate the differences in conformational entropy between chains in single crystals and chains in twinned crystals, and find that the reduction in chain conformational entropy in the twin is sufficient to make the single crystal the stable thermodynamic phase. The formation of cyclic twins in molecular dynamics simulations of chains of hard spheres must thus be attributed to kinetic factors. In more realistic polymers this entropic contribution to the free energy can be canceled or dominated by nonbonded and torsional energetics.

Pregnancy outcome of monochorionic twins: does amnionicity matter?

Science.gov (United States)

Dias, Thiran; Contro, Elena; Thilaganathan, Basky; Khan, Hina; Zanardini, Cristina; Mahsud-Dornan, Samina; Bhide, Amar

2011-12-01

To compare the fetal loss rate of monochorionic (MC) twin pregnancies according to their amnionicity. A retrospective review of all MC pregnancy outcomes in a tertiary centre. Pregnancy outcomes were compared for monochorionic monoamniotic (MCMA) versus monochorionic diamniotic (MCDA) pregnancies. 29 MCMA and 117 MCDA twin pregnancies were identified. The overall fetal loss rate was significantly higher in MCMA (23/52, 44.2%) compared to MCDA pregnancies (28/233, 12%, Chi squared = 30.03, p fetal survival rate in MCDA twins were significantly higher than in MCMA twins (Log-rank Chi-squared = 27.9, p fetal losses in some MCMA twins. After exclusion of identifiable causes, the difference in fetal survival was not significant in the two groups (Log-rank chi-squared = 0.373, p = .54). The loss rate for MCMA twins is high and occurs mainly due to discordant congenital abnormality, conjoint twins or twin reversed arterial perfusion (TRAP) sequence. Although the fetal loss rate in MCDA is lower than in MCMA pregnancies, the majority of fetal loss in MCDA pregnancies cannot be predicted at the first scan at presentation. The data of this study questions the widespread policy of a difference in the scheduling of elective delivery for MCMA and MCDA twins.

Risk of epilepsy in opposite-sex and same-sex twins

DEFF Research Database (Denmark)

Mao, Yanyan; Ahrenfeldt, Linda Juel; Christensen, Kaare

2018-01-01

Background: There is a complex interaction between female and male sex hormones and the risk of epilepsy. Whether prenatal exposure to higher levels of sex hormones affects the development of epilepsy in childhood or later in life is not well known. The sex hormone environment of fetuses may...... be affected by the sex of the co-twin. We estimated the risk of epilepsy for twins with an opposite-sex (OS) co-twin compared with twins with a same-sex (SS) co-twin. Methods: From the Danish Twin Registry, we identified OS female twins (n = 11,078), SS female twins (n = 19,186), OS male twins (n = 11...

Evidence for asymptotic safety from lattice quantum gravity.

Science.gov (United States)

Laiho, J; Coumbe, D

2011-10-14

We calculate the spectral dimension for nonperturbative quantum gravity defined via Euclidean dynamical triangulations. We find that it runs from a value of ∼3/2 at short distance to ∼4 at large distance scales, similar to results from causal dynamical triangulations. We argue that the short-distance value of 3/2 for the spectral dimension may resolve the tension between asymptotic safety and the holographic principle.

Twin specific risk factors in primary school achievements.

Science.gov (United States)

de Zeeuw, Eveline L; van Beijsterveldt, Catherina E M; de Geus, Eco J C; Boomsma, Dorret I

2012-02-01

The main aim of this study was to examine twin specific risk factors that influence educational achievement in primary school. We included prenatal factors that are not unique to twins, except for zygosity, but show a higher prevalence in twins than in singletons. In addition, educational achievement was compared between twins and their nontwin siblings in a within-family design. Data were obtained from parents and teachers of approximately 10,000 twins and their nontwin siblings registered with the Netherlands Twin Register. Teachers rated the proficiency of the children on arithmetic, language, reading, and physical education, and reported a national educational achievement test score (CITO). Structural equation modeling showed that gestational age, birth weight, and sex were significant predictors of educational achievement, even after correction for socioeconomic status. Mode of delivery and zygosity did not have an effect, while parental age only influenced arithmetic. Mode of conception, incubator time, and birth complications negatively affected achievement in physical education. The comparison of educational achievement of twins and singletons showed significantly lower ratings on arithmetic, reading, and language in twins, compared to their older siblings, but not compared to their younger siblings. Low gestational age and low birth weight were the most important risk factors for lower educational achievement of twins in primary school. It seems that the differences observed between twins and their nontwin siblings in educational achievement can largely be explained by birth order within the family.

Conjoined twins – role of imaging and recent advances

Directory of Open Access Journals (Sweden)

Rishi Philip Mathew

2017-12-01

Full Text Available Introduction: Conjoined twins are identical twins with fused bodies, joined in utero. They are rare complications of monochorionic twinning. The purpose of this study is to describe the various types of conjoined twins, the role of imaging and recent advances aiding in their management. Material and methods: This was a twin institutional study involving 3 cases of conjoined twins diagnosed over a period of 6 years from 2010 to 2015. All the 3 cases were identified antenatally by ultrasound. Only one case was further evaluated by MRI. Results: Three cases of conjoined twins (cephalopagus, thoracopagus and omphalopagus were accurately diagnosed on antenatal ultrasound. After detailed counseling of the parents and obtaining written consent, all the three cases of pregnancy were terminated. Delivery of the viable conjoined twins was achieved without any complications to the mothers, and all the three conjoined twins died after a few minutes. Conclusion: Ultrasound enables an early and accurate diagnosis of conjoined twins, which is vital for obstetric management. MRI is reserved for better tissue characterization. Termination of pregnancy when opted, should be done at an early stage as later stages are fraught with problems. Recent advances, such as 3D printing, may aid in surgical pre-planning, thereby enabling successful surgical separation of conjoined twins.

Laying the ghost of twin paradox

Directory of Open Access Journals (Sweden)

Popović Marko

2009-01-01

Full Text Available Someone's true age is not written in his ID, but in his biomarkers. Aging process is not caused by time passing, but by thermodynamically laws. Entropy, extent of metabolic reaction, and temperature are Lorentz invariant, so these facts make twin paradox impossible because there is no way for one twin to age slower than the other even if the time in his frame is dilated. Entropy is the function of state, not time. So as much as standard thermodynamics concerns, the path between two points in space is equivalent to the path between two states. Whether the point B is reached by moving faster using the longer way (with time dilatation, or slower by using shortcut (without time dilatation, the state of the system after completing the road should be the same. This is supported by the fact that when two twins reach the same space-time point (point B in which the state parameters are the same. If we use entropy as an age parameter, then both twins have the same entropy value and are exactly the same biological age. Therefore, the twin paradox is a logical mistake based on wrong first premise. Bergson symmetry is not necessary any more to explain the impossibility of twin paradox.

The Concordance and Heritability of Type 2 Diabetes in 34,166 Twin Pairs From International Twin Registers

DEFF Research Database (Denmark)

Willemsen, G.; Ward, K. J.; Bell, C. G.

2015-01-01

studies worldwide need to pool their resources. The Discordant Twin (DISCOTWIN) consortium was established for this goal. Here, we describe the DISCOTWIN Consortium and present an analysis of type 2 diabetes (T2D) data in nearly 35,000 twin pairs. Seven twin cohorts from Europe (Denmark, Finland, Norway...... and medication use, fasting glucose and insulin measures, or medical records. The prevalence of T2D ranged from 2.6% to 12.3% across the cohorts depending on age, body mass index (BMI), and national diabetes prevalence. T2D discordance rate was lower for MZ (5.1%, range 2.9-11.2%) than for same-sex dizygotic (DZ......, the Netherlands, Spain, Sweden, and the United Kingdom) and one from Australia investigated the rate of discordance for T2D in same-sex twin pairs aged 45 years and older. Data were available for 34,166 same-sex twin pairs, of which 13,970 were MZ, with T2D diagnosis based on self-reported diagnosis...

Peak effect in twinned superconductors

International Nuclear Information System (INIS)

Larkin, A.I.; Marchetti, M.C.; Vinokur, V.M.

1995-01-01

A sharp maximum in the critical current J c as a function of temperature just below the melting point of the Abrikosov flux lattice has recently been observed in both low- and high-temperature superconductors. This peak effect is strongest in twinned crystals for fields aligned with the twin planes. We propose that this peak signals the breakdown of the collective pinning regime and the crossover to strong pinning of single vortices on the twin boundaries. This crossover is very sharp and can account for the steep drop of the differential resistivity observed in experiments. copyright 1995 The American Physical Society

Effect of twinning plane on superconductor magnetic properties

International Nuclear Information System (INIS)

Buzdin, A.I.; Kuptsov, D.A.

1989-01-01

Effect of twinning planes on pinning of the Abrikosov vortices in superconductors of the second order with the Ginsburg-Landau parameter, κ >> 1, is considered. The modified Ginsburg-Landau functional, where the effect of superconducting properties improvement near the twinning plane is taken into account by adding the additional δ-function component, is used to descibe superconductivity of twinning plane. Force of interaction of a vortex filament and the twinning plane is calculated. It is shown that in case of the twinning plane opaque to electrons, additional attractive force, being analogous to that occurring in the problem on the surface Been-Livingston barrier, affects the vortex filament. The results can explain anisotropy of vortex pinning observed in the periodic twinning structure in high-temperature superconductors

Twin Pregnancy with Gastroschisis in Both Twins

Directory of Open Access Journals (Sweden)

Hui-Fen Kao

2007-12-01

Conclusion: The cause of gastroschisis is unknown, although possible exogenous causes have been studied. The diagnosis of gastroschisis in twin pregnancy is always in late gestation. Therefore, maternal serum alpha feto-protein screening and a detailed prenatal ultrasound evaluation are recommended in multifetal pregnancies.

Temperature dependence of work hardening in sparsely twinning zirconium

International Nuclear Information System (INIS)

Singh, Jaiveer; Mahesh, S.; Roy, Shomic; Kumar, Gulshan; Srivastava, D.; Dey, G.K.; Saibaba, N.; Samajdar, I.

2017-01-01

Fully recrystallized commercial Zirconium plates were subjected to uniaxial tension. Tests were conducted at different temperatures (123 K - 623 K) and along two plate directions. Both directions were nominally unfavorable for deformation twinning. The effect of the working temperature on crystallographic texture and in-grain misorientation development was insignificant. However, systematic variation in work hardening and in the area fraction and morphology of deformation twins was observed with temperature. At all temperatures, twinning was associated with significant near boundary mesoscopic shear, suggesting a possible linkage with twin nucleation. A binary tree based model of the polycrystal, which explicitly accounts for grain boundary accommodation and implements the phenomenological extended Voce hardening law, was implemented. This model could capture the measured stress-strain response and twin volume fractions accurately. Interestingly, slip and twin system hardness evolution permitted multiplicative decomposition into temperature-dependent, and accumulated strain-dependent parts. Furthermore, under conditions of relatively limited deformation twinning, the work hardening of the slip and twin systems followed two phenomenological laws proposed in the literature for non-twinning single-phase face centered cubic materials.

EBSD characterization of twinning in cold-rolled CP-Ti

International Nuclear Information System (INIS)

Li, X.; Duan, Y.L.; Xu, G.F.; Peng, X.Y.; Dai, C.; Zhang, L.G.; Li, Z.

2013-01-01

This work presents the use of a mechanical testing system and the electron backscatter diffraction technique to study the mechanical properties and twinning systems of cold-rolled commercial purity titanium, respectively. The dependence of twinning on the matrix orientation is analyzed by the distribution map of Schmid factor. The results showed that the commercial purity titanium experienced strong strain hardening and had excellent formability during rolling. Both the (112 ¯ 2) ¯ 3 ¯ > compressive twins and (101 ¯ 2) ¯ 1 ¯ > tensile twins were dependent on the matrix orientation. The Schmid factor of a grain influenced the activation of a particular twinning system. The specific rolling deformation of commercial purity titanium controlled the number and species of twinning systems and further changed the mechanical properties. - Highlights: • CP-Ti experienced strain hardening and had excellent formability. • Twins were dependent on the matrix orientation. • Schmid factor of a grain influenced the activation of a twinning system. • Rolling deformation controlled twinning systems and mechanical properties

Socio-psycho-historical observation on the twin

International Nuclear Information System (INIS)

Watanabe, Shoji; Satow, Yukio; Ueoka, Hiroshi; Munaka, Masaki; Kurihara, Minoru

1980-01-01

The so-called ''twin control study'', mainly on the monozygotic twins one of which was A-bomb exposed and the other was non-exposed were carried out. Sampling was conducted utilizing the materials as follows: 1) The survey on casualities of A-bomb exposed families in Hiroshima which was undertaken in 1946. 2) The survey of A-bomb survivors in 1965. 3) A-bomb exposed family survey conducted between 1973 to 1975. 4) Investigations of A-bomb victims exposed in the proximal areas from the hypocenter. From the above mentioned materials 470 pairs were selected, of which 220 were exposed. Among them 172 pairs were twins of the same sex. Female and male pair were also employed. In one case they were exposed, while the others were nonexposed. Two pairs were examined under the following methods: 1) Depth interview to ascertain familial casualities with reference to the family life cycle. 2) Socio-historical research. 3) Motoaki's Jinkaku Shindan Kensa (Modified Rorschach test by H. Motoaki), and T.A.T. test. Results obtained were summarized as follows: 1) Both pairs of twins were similar appearance, and also personality traits, and had a strong feeling of companionship for each other. 2) In family relationships, the persons studied were very conscious of the role expectations of elder and younger siblings in the twin pairs. 3) Through depth interview and projective test, A-bomb exposed pairs still showed deep psychological stresses, resulting from the A-bomb disaster. 4) Both among the exposed twins and within the nonexposed control group twin siblings had a close feeling of companionship for each other. However, nonexposed twins could not understand the psychological experience of twins who had been subjected to the atomic disaster. (author)

Postpartum Mental State of Mothers of Twins

Science.gov (United States)

Brantmüller, Éva; Gyúró, Mónika; Galgán, Kitti; Pakai, Annamária

2016-01-01

Twin birth is a relevant risk factor for postnatal depression (PND). The primary objective of our study is to reveal the prevalence of suspected cases of depression and to identify some background factors among mothers of twins. We applied convenience sampling method within a retrospective, quantitative study among mothers given birth to twins for…

Hydride formation on deformation twin in zirconium alloy

Energy Technology Data Exchange (ETDEWEB)

Kim, Ju-Seong [Korea Atomic Energy Research Institute, 989-111 Daedeokdaero, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of); Kim, Sung-Dae [Korea Institute of Material Science (KIMS), 797 Changwondaero, Changwon, Gyeongnam, 642-831 (Korea, Republic of); Yoon, Jonghun, E-mail: yooncsmd@gmail.com [Department of Mechanical Engineering, Hanyang University, 1271 Sa3-dong, Sangrok-gu, Ansan-si, Gyeonggi-do, 426-791 (Korea, Republic of)

2016-12-15

Hydrides deteriorate the mechanical properties of zirconium (Zr) alloys used in nuclear reactors. Intergranular hydrides that form along grain boundaries have been extensively studied due to their detrimental effects on cracking. However, it has been little concerns on formation of Zr hydrides correlated with deformation twins which is distinctive heterogeneous nucleation site in hexagonal close-packed metals. In this paper, the heterogeneous precipitation of Zr hydrides at the twin boundaries was visualized using transmission electron microscopy. It demonstrates that intragranular hydrides in the twinned region precipitates on the rotated habit plane by the twinning and intergranular hydrides precipitate along the coherent low energy twin boundaries independent of the conventional habit planes. Interestingly, dislocations around the twin boundaries play a substantial role in the nucleation of Zr hydrides by reducing the misfit strain energy.

New theory for crack-tip twinning in fcc metals

Science.gov (United States)

Andric, Predrag; Curtin, W. A.

2018-04-01

Dislocation emission from a crack tip is a necessary mechanism for crack tip blunting and toughening. In fcc metals under Mode I loading, a first partial dislocation is emitted, followed either by a trailing partial dislocation ("ductile" behaviour) or a twinning partial dislocation ("quasi-brittle"). The twinning tendency is usually estimated using the Tadmor and Hai extension of the Rice theory. Extensive molecular statics simulations reveal that the predictions of the critical stress intensity factor for crack tip twinning are always systematically lower (20-35%) than observed. Analyses of the energy change during nucleation reveal that twin partial emission is not accompanied by creation of a surface step while emission of the trailing partial creates a step. The absence of the step during twinning motivates a modified model for twinning nucleation that accounts for the fact that nucleation does not occur directly at the crack tip. Predictions of the modified theory are in excellent agreement with all simulations that show twinning. Emission of the trailing partial dislocation, including the step creation, is predicted using a model recently introduced to accurately predict the first partial emission and shows why twinning is preferred. A second mode of twinning is found wherein the crack first advances by cleavage and then emits the twinning partial at the new crack tip; this mode dominates for emission beyond the first twinning partial. These new theories resolve all the discrepancies between the Tadmor twinning analysis and simulations, and have various implications for fracture behaviour and transitions.

Temperament and character in the Child and Adolescent Twin Study in Sweden (CATSS: comparison to the general population, and genetic structure analysis.

Directory of Open Access Journals (Sweden)

Danilo Garcia

Full Text Available BACKGROUND: The Child and Adolescent Twin Study in Sweden (CATSS is an on-going, large population-based longitudinal twin study. We aimed (1 to investigate the reliability of two different versions (125-items and 238-items of Cloninger's Temperament and Character Inventory (TCI used in the CATSS and the validity of extracting the short version from the long version, (2 to compare these personality dimensions between twins and adolescents from the general population, and (3 to investigate the genetic structure of Cloninger's model. METHOD: Reliability and correlation analyses were conducted for both TCI versions, 2,714 CATSS-twins were compared to 631 adolescents from the general population, and the genetic structure was investigated through univariate genetic analyses, using a model-fitting approach with structural equation-modeling techniques based on same-sex twin pairs from the CATSS (423 monozygotic and 408 dizygotic pairs. RESULTS: The TCI scores from the short and long versions showed comparable reliability coefficients and were strongly correlated. Twins scored about half a standard deviation higher in the character scales. Three of the four temperament dimensions (Novelty Seeking, Harm Avoidance, and Persistence had strong genetic and non-shared environmental effects, while Reward Dependence and the three character dimensions had moderate genetic effects, and both shared and non-shared environmental effects. CONCLUSIONS: Twins showed higher scores in character dimensions compared to adolescents from the general population. At least among adolescents there is a shared environmental influence for all of the character dimensions, but only for one of the temperament dimensions (i.e., Reward Dependence. This specific finding regarding the existence of shared environmental factors behind the character dimensions in adolescence, together with earlier findings showing a small shared environmental effects on character among young adults and no

Congenital Chagas's disease in an urban population: investigation of infected twins.

Science.gov (United States)

Hoff, R; Mott, K E; Milanesi, M L; Bittencourt, A L; Barbosa, H S

1978-01-01

In the Nordeste de Amaralina suburb of Salvador Bahia, Brazil, 47 of 285 pregnant women surveyed had complement fixing antibodies to Trypanosoma cruzi. At delivery T. cruzi was detected in one of 17 placentas from the sero-positive women. The offspring of this case were premature twins and T. cruzi was detected in the peripheral blood of each before death. At autopsy the gastro-intestinal tract and urinary bladder of both were severely affected. Immunofluorescence tests on cord sera, including the single case with T. cruzi in the placenta, were negative for IgM antibodies to T. cruzi. The mother of the infected twins and three of her living children, who were born and have resided in the city, were also infected with T. cruzi. Although the children had visited an area endemic for Chagas's disease for short periods, the mode of transmission in this family may have been transplacental. The value of the immunofluorescence test in the diagnosis of congenital Chagas's disease is discussed.

A Combined Gravity Compensation Method for INS Using the Simplified Gravity Model and Gravity Database.

Science.gov (United States)

Zhou, Xiao; Yang, Gongliu; Wang, Jing; Wen, Zeyang

2018-05-14

In recent decades, gravity compensation has become an important way to reduce the position error of an inertial navigation system (INS), especially for a high-precision INS, because of the extensive application of high precision inertial sensors (accelerometers and gyros). This paper first deducts the INS's solution error considering gravity disturbance and simulates the results. Meanwhile, this paper proposes a combined gravity compensation method using a simplified gravity model and gravity database. This new combined method consists of two steps all together. Step 1 subtracts the normal gravity using a simplified gravity model. Step 2 first obtains the gravity disturbance on the trajectory of the carrier with the help of ELM training based on the measured gravity data (provided by Institute of Geodesy and Geophysics; Chinese Academy of sciences), and then compensates it into the error equations of the INS, considering the gravity disturbance, to further improve the navigation accuracy. The effectiveness and feasibility of this new gravity compensation method for the INS are verified through vehicle tests in two different regions; one is in flat terrain with mild gravity variation and the other is in complex terrain with fierce gravity variation. During 2 h vehicle tests, the positioning accuracy of two tests can improve by 20% and 38% respectively, after the gravity is compensated by the proposed method.

Do assisted-reproduction twin pregnancies require additional antenatal care?

Science.gov (United States)

Jauniaux, E; Ben-Ami, I; Maymon, R

2013-02-01

Iatrogenic twinning has become the main side-effect assisted reproduction treatment. We have evaluated the evidence for additional care that assisted-reproduction twins may require compared with spontaneous twins. Misacarriages are increased in women with tubal problems and after specific treatments. Assisted-reproduction twin pregnancies complicated by a vanishing twin after 8 weeks have an increased risk of preterm delivery and of low and very low birthweight compared with singleton assisted-reproduction pregnancies. Monozygotic twin pregnancies occur at a higher rate after assisted reproduction treatment and are associated with a higher risk of perinatal complications. The incidence of placenta praevia and vasa praevia is increased in assisted-reproduction twin pregnancies. Large cohort studies do not indicate a higher rate of fetal congenital malformations in assisted-reproduction twins. Overall, assisted-reproduction twins in healthy women assisted-reproduction twins is only increased in women with a pre-existing medical condition such as hypertensive disorders and diabetes and most of these risks can be avoided with single-embryo transfer. Following the birth of the first IVF baby, rumours started to spread in both the medical literature and the media about the long-term health effects for children born following assisted reproduction treatment. However, after more than 30 years, the most common complications associated with IVF treatment remain indirect and technical such as the failure of treatment and ovarian hyperstimulation. Iatrogenic twinning has become the main side-effect of assisted reproduction treatment and the increasing number of twin pregnancies, in particular in older women, has generated numerous debates on the need for additional healthcare provision. In this review, we have evaluated the evidence for additional care that assisted-conception twin pregnancies may require compared with spontaneous twin pregnancies. Twin pregnancies are

Dichorionic Diamniotic Twin Pregnancy Discordant for Bladder Exstrophy

Directory of Open Access Journals (Sweden)

William Tu

2009-01-01

Full Text Available A 38 year-old woman presented with a dichorionic diamniotic twin pregnancy at gestational age of 32 weeks concerning for an abdominal wall mass in one of the twins. Initial ultrasound evaluation was suspicious for an omphalocele, but the affected twin was found to have bladder exstrophy at birth. This illustrates the difficulties of accurate prenatal diagnosis of bladder exstrophy in a twin pregnancy at a late gestation.

A note on twin-singleton differences in asthma

DEFF Research Database (Denmark)

Thomsen, Simon Francis; Kyvik, Kirsten Ohm; Backer, Vibeke

2008-01-01

Twins constitute a valuable resource for genetic studies of asthma. However, critics argue that twins are 'special' in terms of prenatal environment and upbringing and therefore nonrepresentative. In respect to asthma a small range of studies report differential morbidity in twins compared...... with singletons. We review some of the possible explanations for these findings and conclude that results from twin studies of asthma can be extrapolated to the general population....

Epigenetic Epidemiology of Complex Diseases Using Twins

DEFF Research Database (Denmark)

Tan, Qihua

2013-01-01

through multiple epigenetic mechanisms. This paper reviews the new developments in using twins to study disease-related epigenetic alterations, links them to lifetime environmental exposure with a focus on the discordant twin design and proposes novel data-analytical approaches with the aim of promoting...... a more efficient use of twins in epigenetic studies of complex human diseases....

Twin Studies of Atopic Dermatitis

DEFF Research Database (Denmark)

Elmose, Camilla; Thomsen, Simon Francis

2015-01-01

Aim. The aim of this study was to conduct a systematic review of population-based twin studies of (a) the concordance and heritability of AD and (b) the relationship between AD and asthma and, furthermore, to reinterpret findings from previous twin studies in the light of the emerging knowledge a...

Monozygotic twins discordant for ROHHAD phenotype.

Science.gov (United States)

Patwari, Pallavi P; Rand, Casey M; Berry-Kravis, Elizabeth M; Ize-Ludlow, Diego; Weese-Mayer, Debra E

2011-09-01

Rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD) falls within a group of pediatric disorders with both respiratory control and autonomic nervous system dysregulation. Children with ROHHAD typically present after 1.5 years of age with rapid weight gain as the initial sign. Subsequently, they develop alveolar hypoventilation, autonomic nervous system dysregulation, and, if untreated, cardiorespiratory arrest. To our knowledge, this is the first report of discordant presentation of ROHHAD in monozygotic twins. Twin girls, born at term, had concordant growth and development until 8 years of age. From 8 to 12 years of age, the affected twin developed features characteristic of ROHHAD including obesity, alveolar hypoventilation, scoliosis, hypothalamic dysfunction (central diabetes insipidus, hypothyroidism, premature pubarche, and growth hormone deficiency), right paraspinal/thoracic ganglioneuroblastoma, seizures, and autonomic dysregulation including altered pain perception, large and sluggishly reactive pupils, hypothermia, and profound bradycardia that required a cardiac pacemaker. Results of genetic testing for PHOX2B (congenital central hypoventilation syndrome disease-defining gene) mutations were negative. With early recognition and conservative management, the affected twin had excellent neurocognitive outcome that matched that of the unaffected twin. The unaffected twin demonstrated rapid weight gain later in age but not development of signs/symptoms consistent with ROHHAD. This discordant twin pair demonstrates key features of ROHHAD including the importance of early recognition (especially hypoventilation), complexity of signs/symptoms and clinical course, and importance of initiating comprehensive, multispecialty care. These cases confound the hypothesis of a monogenic etiology for ROHHAD and indicate alternative etiologies including autoimmune or epigenetic phenomenon or a combination of genetic

Molecular dynamics simulation of deformation twin in rocksalt vanadium nitride

International Nuclear Information System (INIS)

Fu, Tao; Peng, Xianghe; Zhao, Yinbo; Li, Tengfei; Li, Qibin; Wang, Zhongchang

2016-01-01

We perform molecular dynamics simulation of nano-indentation with a cylindrical indenter to investigate the formation mechanism of deformation twin in vanadium nitride (VN) with a rocksalt structure. We find that the deformation twins occur during the loading stage, and subsequently conduct a systematic analysis of nucleation, propagation and thickening of a deformation twin. We find that the nucleation of a partial dislocation and its propagation to form a stacking fault are premise of deformation twin formation. The sequential nucleation and propagation of partial dislocation on adjacent parallel {111} planes are found to cause the thickening of the deformation twin. Moreover, the deformation twins can exist in VN at room temperature. - Highlights: • MD simulations of indentation are performed to study the deformation twin in VN. • The deformation twins can occur in VN during the loading stage. • The nucleation, propagation and thickening of a deformation twin are analyzed. • The deformation twins can exist in VN at room temperature.

Gene-Environment Interplay in Twin Models

OpenAIRE

Verhulst, Brad; Hatemi, Peter K.

2013-01-01

In this article, we respond to Shultziner’s critique that argues that identical twins are more alike not because of genetic similarity, but because they select into more similar environments and respond to stimuli in comparable ways, and that these effects bias twin model estimates to such an extent that they are invalid. The essay further argues that the theory and methods that undergird twin models, as well as the empirical studies which rely upon them, are unaware of these potential biases...

High energy scattering in gravity and supergravity

CERN Document Server

Giddings, Steven B; Andersen, Jeppe R

2010-01-01

We investigate features of perturbative gravity and supergravity by studying scattering in the ultraplanckian limit, and sharpen arguments that the dynamics is governed by long-distance physics. A simple example capturing aspects of the eikonal resummation suggests why short distance phenomena and in particular divergences or nonrenormalizability do not necessarily play a central role in this regime. A more profound problem is apparently unitarity. These considerations can be illustrated by showing that known gravity and supergravity amplitudes have the same long-distance behavior, despite the extra light states of supergravity, and this serves as an important check on long-range dynamics in a context where perturbative amplitudes are finite. We also argue that these considerations have other important implications: they obstruct probing the conjectured phenomenon of asymptotic safety through a physical scattering process, and gravity appears not to reggeize. These arguments sharpen the need to find a nonpert...

Conjoined twin piglets with duplicated cranial and caudal axes.

Science.gov (United States)

McManus, C A; Partlow, G D; Fisher, K R

1994-06-01

Twins with doubling of the cranial and caudal poles, yet having a single thorax, are rare. One set of diprosopus, dipygus porcine conjoined twins was studied. In addition to the conjoining anomaly, these twins also exhibited ambiguous internal reproductive features. The twins had two snouts, three eyes, a single thorax, and were duplicated from the umbilicus caudally. Radiography indicated a single vertebral column in the cervical region. The vertebral columns were separate caudally from this point. There was a total of six limbs--one pair of forelimbs and two pairs of hindlimbs. Many medial structures failed to develop in these twins. Medial cranial nerves V-XII were absent or displaced although apparently normal laterally. The medial palates were present but shortened, whereas the medial mandibular rami had folded back on themselves rostrally to form a midline mass between the two chins. Each twin had only one lateral kidney and one lateral testis. Medial scrotal sacs were present but devoid of a testis. There was a midline, "uterine"-like structure which crossed between the twins. However, histological analysis of this structure revealed it to be dysplastic testicular tissue. The relationship between the abnormal reproductive features in these twins and the conjoining is unclear. The anatomy of these twins, in addition to the literature reviewed, illustrates the internal anatomical heterogeneity of grossly similar conjoined twins. A review of the literature also suggests that conjoined twinning may be more common in swine than was previously suspected.

Recurrent twin-twin transfusion syndrome after selective fetoscopic laser photocoagulation: a systematic review of the literature.

LENUS (Irish Health Repository)

Walsh, C A

2012-11-01

Selective fetoscopic laser photocoagulation (SFLP) is now the treatment of choice for twin-twin transfusion syndrome (TTTS). The incidence of recurrent TTTS following SFLP has been inconsistently reported across different studies. We performed a systematic review of TTTS recurrence following SFLP.

Disease-Concordant Twins Empower Genetic Association Studies

DEFF Research Database (Denmark)

Tan, Qihua; Li, Weilong; Vandin, Fabio

2017-01-01

and ordinary healthy samples as controls. We examined the power gain of the twin-based design for various scenarios (i.e., cases from monozygotic and dizygotic twin pairs concordant for a disease) and compared the power with the ordinary case-control design with cases collected from the unrelated patient...... concordant for a disease, should confer increased power in genetic association analysis because of their genetic relatedness. We conducted a computer simulation study to explore the power advantage of the disease-concordant twin design, which uses singletons from disease-concordant twin pairs as cases...... population. Simulation was done by assigning various allele frequencies and allelic relative risks for different mode of genetic inheritance. In general, for achieving a power estimate of 80%, the sample sizes needed for dizygotic and monozygotic twin cases were one half and one fourth of the sample size...

Increased risk of abortion after genetic amniocentesis in twin pregnancies

DEFF Research Database (Denmark)

Palle, C; Andersen, J W; Tabor, A

1983-01-01

Forty-seven twin pregnancies among 3676 patients who had a genetic amniocentesis between 1973 and 1979, are reported. The detection rate of twins at the time of amniocentesis was 62 per cent. Five (17 per cent) of the 29 women with detected twin pregnancy aborted spontaneously, these are compared...... in at least one sac aborted, while 3 of 20 twin pregnancies with one puncture in each sac aborted (15 per cent). One of 18 (6 per cent) twin pregnancies, where only one sac was punctured, because the twin pregnancies were undetected, aborted. Amniocentesis of both sacs in twin pregnancies seems associated...... with an increased risk of spontaneous abortion. The indications for amniocentesis in twin pregnancies should be critically evaluated....

Sonographic monitoring of complications and anomalies in twin gestations

International Nuclear Information System (INIS)

Coleman, B.G.; Grumbach, K.; Arger, P.H.; Mintz, M.C.; Arenson, R.L.; Mennuti, M.T.; Gabbe, S.G.

1986-01-01

One hundred sixty-eight twin gestations were evaluated to assess the role of US in the diagnosis of obstetric complications and anomalies. US revealed the following complications: symptomatic polyhydramnios (eight cases), myomas (seven), placenta previa (three), and abruption (five). Fetal anomalies included twin-twin transfusion syndrome (two), acardiac anomaly (two), chromosomal abnormality (two), anencephaly (one), hydrocephaly (one), and conjoined twins (two). In 26 gestations intrauterine fetal demise or neonatal death involved one or both twins for a total of 42 deaths, constituting a mortality of 12.5%. No maternal deaths occurred. The impact of sonographic monitoring on the obstetric management of twin gestations is emphasized

The five factor model of personality and intelligence: A twin study on the relationship between the two constructs

NARCIS (Netherlands)

Bartels, M.; van Weegen, F.I.; van Beijsterveldt, C.E.M.; Carlier, M.; Polderman, T.J.C.; Hoekstra, R.A.; Boomsma, D.I.

2012-01-01

We assessed the association and underlying genetic and environmental influences among intelligence (IQ) and personality in adolescent and young adult twins. Data on intelligence were obtained from psychometric IQ tests and personality was assessed with the short form of the NEO five factor inventory

Twinning in Zircon: Not a High-Pressure Phenomenon

Science.gov (United States)

Jones, G. A.; Moser, D.; Shieh, S. R.; Barker, I.

2017-12-01

Microtwins in zircon are commonly found in shocked terrestrial and extraterrestrial samples and are potentially important for shock history and crater reconstruction. Twinning is easily observed with both the optical microscope and variety of electron beam techniques. Twinning as a deformation mechanism is consistent with the high strain rates generated during impact. No constitutive relationships, or even general limits on the physical conditions required for twinning in zircon are known, however. Present speculation on the critical quantity for twin formation, i.e. 10s of GPa of shock pressure (Moser et al. 2011, Timms et al., 2012), has no basis in the underlying mechanisms of twin nucleation, which are related to the motion of dislocations. This erroneous value is due to conflation of twinning sensu stricto with a phase transformation to reidite. Reidite occurs as twin-like lamellae occupying the {112} planes which are thought to be a mirror plane for twinning. We review the crystallographic theory of twinning in zircon. We then evaulate several theories on the nucleation of twins along with their necessary stresses involved. Our aim is to show that shock microtwins in zircon can be a `low pressure' shock phenomenon. This 'low pressure' hypothesis is supported by natural samples. These zircons are from the lower crust nearly 80 km from the centre of the Vredefort impact structure—the most distal zircon shock microstructures yet found in the lithosphere. Twins are present in 10% of the zircon grains greater than 50 µm in diameter. As an extensive, 'low pressure' phenomenon, twins are an easily recognized and potentially widespread record of Earth's impact history.Moser, D.E., Cupelli, C. L., Barker, I., Flowers, R. M., Mowman, J. R., Wooden, J. and Hart, R. (2011) New zircon shock phenomena and their use for dating and […] analysis of the Vredefort dome, Canadian Journal of Earth Sciences 48(2), 117-139.Timms, N.E., Reddy, S. M., Healy, D., Nemchin, A. A

Late language emergence in 24-month-old twins: heritable and increased risk for late language emergence in twins.

Science.gov (United States)

Rice, Mabel L; Zubrick, Stephen R; Taylor, Catherine L; Gayán, Javier; Bontempo, Daniel E

2014-06-01

This study investigated the etiology of late language emergence (LLE) in 24-month-old twins, considering possible twinning, zygosity, gender, and heritability effects for vocabulary and grammar phenotypes. A population-based sample of 473 twin pairs participated. Multilevel modeling estimated means and variances of vocabulary and grammar phenotypes, controlling for familiality. Heritability was estimated with DeFries-Fulker regression and variance components models to determine effects of heritability, shared environment, and nonshared environment. Twins had lower average language scores than norms for single-born children, with lower average performance for monozygotic than dizygotic twins and for boys than girls, although gender and zygosity did not interact. Gender did not predict LLE. Significant heritability was detected for vocabulary (0.26) and grammar phenotypes (0.52 and 0.43 for boys and girls, respectively) in the full sample and in the sample selected for LLE (0.42 and 0.44). LLE and the appearance of Word Combinations were also significantly heritable (0.22-0.23). The findings revealed an increased likelihood of LLE in twin toddlers compared with single-born children that is modulated by zygosity and gender differences. Heritability estimates are consistent with previous research for vocabulary and add further suggestion of heritable differences in early grammar acquisition.

The Spread of Substance Use and Delinquency between Adolescent Twins

Science.gov (United States)

Laursen, Brett; Hartl, Amy C.; Vitaro, Frank; Brendgen, Mara; Dionne, Ginette; Boivin, Michel

2017-01-01

This investigation examines the spread of problem behaviors (substance use and delinquency) between twin siblings. A sample of 628 twins (151 male twin pairs and 163 female twin pairs) drawn from the Quebec Newborn Twin Study completed inventories describing delinquency and substance use at ages 13, 14, and 15. A 3-wave longitudinal actor-partner…

Giersch International Symposion 2016 : Week 1 : Experimental Search for Quantum Gravity

CERN Document Server

Experimental Search for Quantum Gravity

2018-01-01

This book summarizes recent developments in the research area of quantum gravity phenomenology. A series of short and nontechnical essays lays out the prospects of various experimental possibilities and their current status. Finding observational evidence for the quantization of space-time was long thought impossible. In the last decade however, new experimental design and technological advances have changed the research landscape and opened new perspectives on quantum gravity. Formerly dominated by purely theoretical constructions, quantum gravity now has a lively phenomenology to offer. From high precision measurements using macroscopic quantum oscillators to new analysis methods of the cosmic microwave background, no stone is being left unturned in the experimental search for quantum gravity. This book sheds new light on the connection of astroparticle physics with the quantum gravity problem. Gravitational waves and their detection are covered. It illustrates findings from the interconnection between gene...

Atopic diseases in twins born after assisted reproduction

DEFF Research Database (Denmark)

Jäderberg, Ida; Thomsen, Simon F; Kyvik, Kirsten Ohm

2012-01-01

Jäderberg I, Thomsen SF, Kyvik KO, Skytthe A, Backer V. Atopic diseases in twins born after assisted reproduction. Paediatric and Perinatal Epidemiology 2012; 26: 140-145. We examined the risk of atopic diseases in twins born after assisted reproduction. Data on atopic diseases and assisted...... reproduction in 9694 twin pairs, 3-20 years of age, from the Danish Twin Registry were collected via multidisciplinary questionnaires. The risk of atopic diseases in twins born after assisted reproduction was compared with the risk in twins born after spontaneous conception using logistic regression...... and variance components analysis. Children born after assisted reproduction did not have a different risk of atopic outcomes (adjusted odds ratios [95% confidence intervals] for asthma: 0.95 [0.85, 1.07], P = 0.403; hay fever: 1.01 [0.86, 1.18], P = 0.918; and atopic dermatitis: 1.02 [0.81, 1.11], P = 0...

Longitudinal aerodynamic characteristics of light, twin-engine, propeller-driven airplanes

Science.gov (United States)

Wolowicz, C. H.; Yancey, R. B.

1972-01-01

Representative state-of-the-art analytical procedures and design data for predicting the longitudinal static and dynamic stability and control characteristics of light, propeller-driven airplanes are presented. Procedures for predicting drag characteristics are also included. The procedures are applied to a twin-engine, propeller-driven airplane in the clean configuration from zero lift to stall conditions. The calculated characteristics are compared with wind-tunnel and flight data. Included in the comparisons are level-flight trim characteristics, period and damping of the short-period oscillatory mode, and windup-turn characteristics. All calculations are documented.

Indigenous Manufacturing realization of TWIN Source

Science.gov (United States)

Pandey, R.; Bandyopadhyay, M.; Parmar, D.; Yadav, R.; Tyagi, H.; Soni, J.; Shishangiya, H.; Sudhir Kumar, D.; Shah, S.; Bansal, G.; Pandya, K.; Parmar, K.; Vuppugalla, M.; Gahlaut, A.; Chakraborty, A.

2017-04-01

TWIN source is two RF driver based negative ion source that has been planned to bridge the gap between single driver based ROBIN source (currently operational) and eight river based DNB source (to be operated under IN-TF test facility). TWIN source experiments have been planned at IPR keeping the objective of long term domestic fusion programme to gain operational experiences on vacuum immersed multi driver RF based negative ion source. High vacuum compatible components of twin source are designed at IPR keeping an aim on indigenous built in attempt. These components of TWIN source are mainly stainless steel and OFC-Cu. Being high heat flux receiving components, one of the major functional requirements is continuous heat removal via water as cooling medium. Hence for the purpose stainless steel parts are provided with externally milled cooling lines and that shall be covered with a layer of OFC-cu which would be on the receiving side of high heat flux. Manufacturability of twin source components requires joining of these dissimilar materials via process like electrode position, electron beam welding and vacuum brazing. Any of these manufacturing processes shall give a vacuum tight joint having proper joint strength at operating temperature and pressure. Taking the indigenous development effort vacuum brazing (in non-nuclear environment) has been opted for joining of dissimilar materials of twin source being one of the most reliable joining techniques and commercially feasible across the suppliers of country. Manufacturing design improvisation for the components has been done to suit the vacuum brazing process requirement and to ease some of the machining without comprising over the functional and operational requirements. This paper illustrates the details on the indigenous development effort, design improvisation to suits manufacturability, vacuum brazing basics and its procedures for twin source components.

Seasonality in twin birth rates, Denmark, 1936-84.

Science.gov (United States)

Bonnelykke, B; Søgaard, J; Nielsen, J

1987-12-01

A study was made of seasonality in twin birth rate in Denmark between 1977 and 1984. We studied all twin births (N = 45,550) in all deliveries (N = 3,679,932) during that period. Statistical analysis using a simple harmonic sinusoidal model provided no evidence for seasonality. However, sequential polynomial analysis disclosed a significant fit to a fifth order polynomial curve with peaks in twin birth rates in May-June and December, along with troughs in February and September. A falling trend in twinning rate broke off in Denmark around 1970, and from 1970 to 1984 an increasing trend was found. The results are discussed in terms of possible environmental influences on twinning.

Outcome reporting across randomised trials and observational studies evaluating treatments for Twin-Twin Transfusion Syndrome: a systematic review.

Science.gov (United States)

Perry, Helen; Duffy, James M N; Umadia, Ogochukwu; Khalil, Asma

2018-04-01

Twin-Twin Transfusion syndrome is associated with significant mortality and morbidity. Potential treatments require robust evaluation. The aim of this study was to evaluate outcome reporting across observational studies and randomised controlled trials assessing treatments for twin-twin transfusion syndrome (TTTS). Cochrane Central Register of Controlled Trials, EMBASE and Medline were searched from inception to August 2016. Observational studies and randomised controlled trials reporting outcomes following a treatment for TTTS in monochorionic-diamniotic twin pregnancies and monochorionic-triamniotic or dichorionic-triamniotic triplet pregnancies were included. We systematically extracted and categorised outcome reporting. Six randomised trials and 94 observational studies, reporting data from 20,071 maternal participants and 3,199 children, were included. Six different treatments were evaluated. Included studies reported sixty-two different outcomes, including 10 fetal, 28 neonatal, 6 early childhood and 18 maternal outcomes. The outcomes were inconsistently reported across trials. For example, when considering offspring mortality, 31 studies (31%) reported live birth, 31 studies (31%) reported intrauterine death, 49 studies (49%) reported neonatal mortality, and 17 studies (17%) reported perinatal mortality. Four studies (4%) reported respiratory distress syndrome. Only 19 (19%) of studies were designed for long-term follow-up and 11 of these studies (11%) reported cerebral palsy. Most studies evaluating treatments for TTTS, have often neglected to report clinically important outcomes, especially neonatal morbidity outcomes. Most studies are not designed for long-term follow-up. The development of a core outcome set could help standardised outcome collection and reporting in Twin-Twin Transfusion syndrome studies. This article is protected by copyright. All rights reserved.

Newtonian gravity in loop quantum gravity

OpenAIRE

Smolin, Lee

2010-01-01

We apply a recent argument of Verlinde to loop quantum gravity, to conclude that Newton's law of gravity emerges in an appropriate limit and setting. This is possible because the relationship between area and entropy is realized in loop quantum gravity when boundaries are imposed on a quantum spacetime.

Confined Blood Chimerism in Monochorionic Dizygotic Twins Conceived Spontaneously

Directory of Open Access Journals (Sweden)

Takashi Kanda

2013-05-01

Full Text Available Traditionally, monochorionicity has been regarded as synonymous with monozygosity. However, several recent cases of monochorionic dizygotic twins have shown that monochorionic twins can be dizygous. We report a rare case of monochorionic diamnionic, gender-discordant twins who were conceived spontaneously. Initially, a monochorionic placenta was diagnosed by ultrasonography at 8 weeks of gestation and then confirmed by pathology after delivery. The twins had different genders. A comparison of cytogenetic analyses using peripheral blood lymphocytes and skin fibroblasts revealed that chimerism was confined to blood cells. We have experienced two cases of monochorionic dizygotic twins since 2003. These cases suggest that monochorionic dizygotic twins are not as rare as previously thought.

Does the sex of one's co-twin affect height and BMI in adulthood? A study of dizygotic adult twins from 31 cohorts.

Science.gov (United States)

Bogl, Leonie H; Jelenkovic, Aline; Vuoksimaa, Eero; Ahrenfeldt, Linda; Pietiläinen, Kirsi H; Stazi, Maria A; Fagnani, Corrado; D'Ippolito, Cristina; Hur, Yoon-Mi; Jeong, Hoe-Uk; Silberg, Judy L; Eaves, Lindon J; Maes, Hermine H; Bayasgalan, Gombojav; Narandalai, Danshiitsoodol; Cutler, Tessa L; Kandler, Christian; Jang, Kerry L; Christensen, Kaare; Skytthe, Axel; Kyvik, Kirsten O; Cozen, Wendy; Hwang, Amie E; Mack, Thomas M; Derom, Catherine A; Vlietinck, Robert F; Nelson, Tracy L; Whitfield, Keith E; Corley, Robin P; Huibregtse, Brooke M; McAdams, Tom A; Eley, Thalia C; Gregory, Alice M; Krueger, Robert F; McGue, Matt; Pahlen, Shandell; Willemsen, Gonneke; Bartels, Meike; van Beijsterveldt, Toos C E M; Pang, Zengchang; Tan, Qihua; Zhang, Dongfeng; Martin, Nicholas G; Medland, Sarah E; Montgomery, Grant W; Hjelmborg, Jacob V B; Rebato, Esther; Swan, Gary E; Krasnow, Ruth; Busjahn, Andreas; Lichtenstein, Paul; Öncel, Sevgi Y; Aliev, Fazil; Baker, Laura A; Tuvblad, Catherine; Siribaddana, Sisira H; Hotopf, Matthew; Sumathipala, Athula; Rijsdijk, Fruhling; Magnusson, Patrik K E; Pedersen, Nancy L; Aslan, Anna K Dahl; Ordoñana, Juan R; Sánchez-Romera, Juan F; Colodro-Conde, Lucia; Duncan, Glen E; Buchwald, Dedra; Tarnoki, Adam D; Tarnoki, David L; Yokoyama, Yoshie; Hopper, John L; Loos, Ruth J F; Boomsma, Dorret I; Sørensen, Thorkild I A; Silventoinen, Karri; Kaprio, Jaakko

2017-01-01

The comparison of traits in twins from opposite-sex (OS) and same-sex (SS) dizygotic twin pairs is considered a proxy measure of prenatal hormone exposure. To examine possible prenatal hormonal influences on anthropometric traits, we compared mean height, body mass index (BMI), and the prevalence of being overweight or obese between men and women from OS and SS dizygotic twin pairs. The data were derived from the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) database, and included 68,494 SS and 53,808 OS dizygotic twin individuals above the age of 20 years from 31 twin cohorts representing 19 countries. Zygosity was determined by questionnaires or DNA genotyping depending on the study. Multiple regression and logistic regression models adjusted for cohort, age, and birth year with the twin type as a predictor were carried out to compare height and BMI in twins from OS pairs with those from SS pairs and to calculate the adjusted odds ratios and 95% confidence intervals for being overweight or obese. OS females were, on average, 0.31 cm (95% confidence interval (CI) 0.20, 0.41) taller than SS females. OS males were also, on average, taller than SS males, but this difference was only 0.14 cm (95% CI 0.02, 0.27). Mean BMI and the prevalence of overweight or obesity did not differ between males and females from SS and OS twin pairs. The statistically significant differences between OS and SS twins for height were small and appeared to reflect our large sample size rather than meaningful differences of public health relevance. We found no evidence to support the hypothesis that prenatal hormonal exposure or postnatal socialization (i.e., having grown up with a twin of the opposite sex) has a major impact on height and BMI in adulthood.

Familial aggregation of atrial fibrillation: a study in Danish twins

DEFF Research Database (Denmark)

Christophersen, Ingrid Elisabeth; Ravn, Lasse Steen; Budtz-Joergensen, Esben

2009-01-01

BACKGROUND: Heritability may play a role in nonfamilial atrial fibrillation (AF). We hypothesized that a monozygotic (MZ) twin whose co-twin was diagnosed with AF would have an increased risk of the disease compared with a dizygotic (DZ) twin in the same situation. METHODS AND RESULTS: A sample......-free survival times, we compared the time span between occurrences of disease in MZ and DZ twins. The unaffected twin was included when his or her twin-sibling (the index twin) was diagnosed with AF. After adjustment for age at entry, MZ twins had a significantly shorter event-free survival time (hazard ratio......, 2.0; 95% CI, 1.3 to 3.0), thereby indicating a genetic component. Using biometric models, we estimated the heritability of AF to be 62% (55% to 68%), due to additive genetics. There were no significant differences across sexes. CONCLUSIONS: All the analyses of twin similarities in the present study...

A global mean dynamic topography and ocean circulation estimation using a preliminary GOCE gravity model

DEFF Research Database (Denmark)

Knudsen, Per; Bingham, R.; Andersen, Ole Baltazar

2011-01-01

The Gravity and steady-state Ocean Circulation Explorer (GOCE) satellite mission measures Earth’s gravity field with an unprecedented accuracy at short spatial scales. In doing so, it promises to significantly advance our ability to determine the ocean’s general circulation. In this study, an ini...

Does anemia-polycythemia complicating twin-twin transfusion syndrome affect outcome after fetoscopic laser surgery?

Science.gov (United States)

Donepudi, R; Papanna, R; Snowise, S; Johnson, A; Bebbington, M; Moise, K J

2016-03-01

Twin anemia-polycythemia sequence (TAPS) can occur as a unique disease or as a complication of twin-twin transfusion syndrome (TTTS). Middle cerebral artery (MCA) Doppler studies are not currently part of the routine evaluation of monochorionic twins since they are not used in the Quintero staging system. As such, the true incidence of TAPS is unknown. We aimed to compare the characteristics and outcomes of twin pregnancies with TTTS complicated by spontaneous anemia-polycythemia vs those with TTTS alone. This was a secondary analysis of data collected prospectively from a cohort of 156 consecutive patients undergoing fetoscopic laser surgery for TTTS, between October 2011 and August 2014. TAPS was defined as discordance in the preoperative MCA peak systolic velocity (PSV), with one twin fetus having MCA-PSV ≤ 1.0 multiples of the median (MoM) and the other having MCA-PSV ≥ 1.5 MoM. Maternal demographics as well as preoperative, operative and postoperative variables were analyzed. Included in the final analysis were 133 patients with complete records: 11 cases with TTTS with anemia-polycythemia and 122 cases with TTTS alone. There was no difference in maternal body mass index, gestational age (GA) at procedure, rate of preterm prelabor rupture of membranes or GA at delivery between the two groups. Patients with TTTS and anemia-polycythemia were more likely to be older (P = 0.03) and parous (P = 0.04) and had a significantly lower number of placental anastomoses (P = 0.01). The dual live-birth rate was similar for both groups (P = 0.76). Cases of TTTS with anemia-polycythemia were more likely to be found in parous and older women and were characterized by fewer vascular anastomoses. TTTS with anemia-polycythemia was not associated with worse perinatal outcome after laser therapy. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Hypothesis test for synchronization: twin surrogates revisited.

Science.gov (United States)

Romano, M Carmen; Thiel, Marco; Kurths, Jürgen; Mergenthaler, Konstantin; Engbert, Ralf

2009-03-01

The method of twin surrogates has been introduced to test for phase synchronization of complex systems in the case of passive experiments. In this paper we derive new analytical expressions for the number of twins depending on the size of the neighborhood, as well as on the length of the trajectory. This allows us to determine the optimal parameters for the generation of twin surrogates. Furthermore, we determine the quality of the twin surrogates with respect to several linear and nonlinear statistics depending on the parameters of the method. In the second part of the paper we perform a hypothesis test for phase synchronization in the case of experimental data from fixational eye movements. These miniature eye movements have been shown to play a central role in neural information processing underlying the perception of static visual scenes. The high number of data sets (21 subjects and 30 trials per person) allows us to compare the generated twin surrogates with the "natural" surrogates that correspond to the different trials. We show that the generated twin surrogates reproduce very well all linear and nonlinear characteristics of the underlying experimental system. The synchronization analysis of fixational eye movements by means of twin surrogates reveals that the synchronization between the left and right eye is significant, indicating that either the centers in the brain stem generating fixational eye movements are closely linked, or, alternatively that there is only one center controlling both eyes.

Prospective risk of fetal death in uncomplicated monochorionic twins.

LENUS (Irish Health Repository)

Farah, Nadine

2012-03-01

A retrospective cohort study was carried out in a university teaching hospital to determine the prospective risk of unexpected fetal death in uncomplicated monochorionic diamniotic (MCDA) twin pregnancies after viability. All MCDA twins delivered at or after 24 weeks\\' gestation from July 1999 to July 2007 were included. Pregnancies with twin-twin transfusion syndrome, growth restriction, structural abnormalities, or twin reversed arterial perfusion sequence were excluded. Of the 144 MCDA twin pregnancies included in our analysis, the risk of intrauterine death was 4.9%. The prospective risk of unexpected intrauterine death was 1 in 43 after 32 weeks\\' gestation and 1 in 37 after 34 weeks\\' gestation. Our results demonstrate that despite close surveillance, the unexpected intrauterine death rate in uncomplicated MCDA twin pregnancies is high. This rate seems to increase after 34 weeks\\' gestation, suggesting that a policy of elective preterm delivery warrants evaluation.

Long-term neurodevelopmental outcome of monochorionic and matched dichorionic twins.

Directory of Open Access Journals (Sweden)

Karien E A Hack

Full Text Available BACKGROUND: Monochorionic (MC twins are at increased risk for perinatal mortality and serious morbidity due to the presence of placental vascular anastomoses. Cerebral injury can be secondary to haemodynamic and hematological disorders during pregnancy (especially twin-to-twin transfusion syndrome (TTTS or intrauterine co-twin death or from postnatal injury associated with prematurity and low birth weight, common complications in twin pregnancies. We investigated neurodevelopmental outcome in MC and dichorionic (DC twins at the age of two years. METHODS: This was a prospective cohort study. Cerebral palsy (CP was studied in 182 MC infants and 189 DC infants matched for weight and age at delivery, gender, ethnicity of the mother and study center. After losses to follow-up, 282 of the 366 infants without CP were available to be tested with the Griffiths Mental Developmental Scales at 22 months corrected age, all born between January 2005 and January 2006 in nine perinatal centers in The Netherlands. Due to phenotypic (unalikeness in mono-or dizygosity, the principal investigator was not blinded to chorionic status; perinatal outcome, with exception of co-twin death, was not known to the examiner. FINDINGS: Four out of 182 MC infants had CP (2.2% - two of the four CP-cases were due to complications specific to MC twin pregnancies (TTTS and co-twin death and the other two cases of CP were the result of cystic PVL after preterm birth - compared to one sibling of a DC twin (0.5%; OR 4.2, 95% CI 0.5-38.2 of unknown origin. Follow-up rate of neurodevelopmental outcome by Griffith's test was 76%. The majority of 2-year-old twins had normal developmental status. There were no significant differences between MC and DC twins. One MC infant (0.7% had a developmental delay compared to 6 DC infants (4.2%; OR 0.2, 95% 0.0-1.4. Birth weight discordancy did not influence long-term outcome, though the smaller twin had slightly lower developmental scores than its

Chiral gravity, log gravity, and extremal CFT

International Nuclear Information System (INIS)

Maloney, Alexander; Song Wei; Strominger, Andrew

2010-01-01

We show that the linearization of all exact solutions of classical chiral gravity around the AdS 3 vacuum have positive energy. Nonchiral and negative-energy solutions of the linearized equations are infrared divergent at second order, and so are removed from the spectrum. In other words, chirality is confined and the equations of motion have linearization instabilities. We prove that the only stationary, axially symmetric solutions of chiral gravity are BTZ black holes, which have positive energy. It is further shown that classical log gravity--the theory with logarithmically relaxed boundary conditions--has finite asymptotic symmetry generators but is not chiral and hence may be dual at the quantum level to a logarithmic conformal field theories (CFT). Moreover we show that log gravity contains chiral gravity within it as a decoupled charge superselection sector. We formally evaluate the Euclidean sum over geometries of chiral gravity and show that it gives precisely the holomorphic extremal CFT partition function. The modular invariance and integrality of the expansion coefficients of this partition function are consistent with the existence of an exact quantum theory of chiral gravity. We argue that the problem of quantizing chiral gravity is the holographic dual of the problem of constructing an extremal CFT, while quantizing log gravity is dual to the problem of constructing a logarithmic extremal CFT.

Twin Specific Risk Factors in Primary School Achievements

NARCIS (Netherlands)

de Zeeuw, L.E.J.; van Beijsterveldt, C.E.M.; de Geus, E.J.C.; Boomsma, D.I.

2012-01-01

The main aim of this study was to examine twin specific risk factors that influence educational achievement in primary school. We included prenatal factors that are not unique to twins, except for zygosity, but show a higher prevalence in twins than in singletons. In addition, educational

Cervical column morphology and craniofacial profiles in monozygotic twins.

Science.gov (United States)

Sonnesen, Liselotte; Pallisgaard, Carsten; Kjaer, Inger

2008-02-01

Previous studies have described the relationships between cervical column morphology and craniofacial morphology. The aims of the present study were to describe cervical column morphology in 38 pairs of adult monozygotic (MZ) twins, and compare craniofacial morphology in twins with fusions with craniofacial morphology in twins without fusion. Visual assessment of cervical column morphology and cephalometric measurements of craniofacial morphology were performed on profile radiographs. In the cervical column, fusion between corpora of the second and third vertebrae was registered as fusion. In the twin group, 8 twin pairs had fusion of the cervical column in both individuals within the pair (sub-group A), 25 pairs had no fusions (subgroup B), and in 5 pairs, cervical column morphology was different within the pair (subgroup C), as one twin had fusion and the other did not. Comparison of craniofacial profiles showed a tendency to increased jaw retrognathia, larger cranial base angle, and larger mandibular inclination in subgroup A than in subgroup B. The same tendency was observed within subgroup C between the individual twins with fusion compared with those without fusion. These results confirm that cervical fusions and craniofacial morphology may be interrelated in twins when analysed on profile radiographs. The study also documents that differences in cervical column morphology can occur in individuals within a pair of MZ twins. It illustrates that differences in craniofacial morphology between individuals within a pair of MZ twins can be associated with cervical fusion.

An elasto-plastic self-consistent model with hardening based on dislocation density, twinning and de-twinning: Application to strain path changes in HCP metals

International Nuclear Information System (INIS)

Zecevic, Milovan; Knezevic, Marko; Beyerlein, Irene J.; Tomé, Carlos N.

2015-01-01

In this work, we develop a polycrystal mean-field constitutive model based on an elastic–plastic self-consistent (EPSC) framework. In this model, we incorporate recently developed subgrain models for dislocation density evolution with thermally activated slip, twin activation via statistical stress fluctuations, reoriented twin domains within the grain and associated stress relaxation, twin boundary hardening, and de-twinning. The model is applied to a systematic set of strain path change tests on pure beryllium (Be). Under the applied deformation conditions, Be deforms by multiple slip modes and deformation twinning and thereby provides a challenging test for model validation. With a single set of material parameters, determined using the flow-stress vs. strain responses during monotonic testing, the model predicts well the evolution of texture, lattice strains, and twinning. With further analysis, we demonstrate the significant influence of internal residual stresses on (1) the flow stress drop when reloading from one path to another, (2) deformation twin activation, (3) de-twinning during a reversal strain path change, and (4) the formation of additional twin variants during a cross-loading sequence. The model presented here can, in principle, be applied to other metals, deforming by multiple slip and twinning modes under a wide range of temperature, strain rate, and strain path conditions

Structures and growth textures of Japanese twin boundaries in quartz

Science.gov (United States)

Momma, K.; Nagase, T.; Kudoh, Y.; Kuribayashi, T.

2008-12-01

Growth textures and atomic configurations of Japanese twin boundaries in quartz were studied by the observation of natural samples and by computational simulations. Samples used in this study are collected from Narushima, Nagasaki Prefecture, Japan. The samples were first polished, and then etched by hydrofluoric acid for several minutes. The etched figures were observed by phase-contrast reflection microscopy and scanning electron microscopy. From these observations, high concentration of Brazil twin lamellae is found near the composition plane of Japanese twin. Observations of cathode luminescence images reveal that the development of Brazil twin lamellae at {112×2} composition plane of Japanese twin is directly related to the preferential growth of Japanese twin along the composition plane. Atomic configurations at {112×2} composition planes of Japanese twin were simulated by using molecular dynamics simulations and the energy minimization method. The simulated structures proved that {112×2} or {1×1×22} composition planes are the only composition planes that do not introduce unsatisfied bonding between Si and O atoms. When the composition plane is different from these planes, some kind of defect structures, like dislocations, are inevitably introduced. In the case of Brazil twin, screw dislocations are also known to be incorporated where orientation of Brazil twin boundary changes from one orientation to another. On the other hand, in the case where Brazil twin boundaries intersect with {112×2} composition planes of Japanese twin, we found that structures are kept coherently without any unsatisfied bonding. This result means that {112×2} composition planes of Japanese twin are the crystallographic sites having more than one possible stacking structures. Observations in this study indicate that {112×2} composition plane of Japanese twin serves as a source of Brazil twin during the course of crystal growth.

Heritability of psoriasis in a large twin sample

DEFF Research Database (Denmark)

Lønnberg, Ann Sophie; Skov, Liselotte; Skytthe, A

2013-01-01

AIM: To study the concordance of psoriasis in a population-based twin sample. METHODS: Data on psoriasis in 10,725 twin pairs, 20-71 years of age, from the Danish Twin Registry was collected via a questionnaire survey. The concordance and heritability of psoriasis were estimated. RESULTS: In total...

Twinning interactions induced amorphisation in ultrafine silicon grains

Energy Technology Data Exchange (ETDEWEB)

Cao, Y. [School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Zhang, L.C., E-mail: liangchi.zhang@unsw.edu.au [School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Zhang, Y. [School of Mechatronics Engineering, Harbin Institute of Technology (China)

2016-03-21

Detailed transmission electron microscopy analysis on a severely deformed Al-Si composite material has revealed that partial dislocation slips and deformation twinning are the major plastic deformation carriers in ultrafine silicon grains. This resembles the deformation twinning activities and mechanisms observed in nano-crystalline face-centred-cubic metallic materials. While deformation twinning and amorphisation in Si were thought unlikely to co-exist, it is observed for the first time that excessive twinning and partial dislocation interactions can lead to localised solid state amorphisation inside ultrafine silicon grains.

Effect of maternal smoking on birth weight of twins: a study from the Dutch Twin Register

NARCIS (Netherlands)

Orlebeke, J.F.; Boomsma, D.I.; van Baal, G.C.M.; Bleker, O.P.

1994-01-01

Since twins weigh about 20% less than singletons at birth, maternal smoking may be a more severe risk for them than for singletons. Therefore, the effect of maternal smoking during pregnancy on birth weight was investigated in a group of 5376 twins. All necessary information was collected by a

Theoretic analysis for gravity separation of water droplets in PWR steam generator

International Nuclear Information System (INIS)

Liu Shixun

1995-10-01

Gravity separation space of water droplets in the PWR steam generator is one of three important separating mechanisms and provides a link between primary (vane) separator and chevron dryer. The design of steam generator should not only have highly efficient and compact separator and dryer, but also an adequate height of gravity separation space. Too short a gravity separation space will not sufficiently separate the moisture and adversely affect the performance of the dryer; too long a gravity separation space will add additional costs for steam generator and nuclear island installation. The droplet entrainment in the process of gravity separation space was theoretically studied and droplet trajectory was analytically modelled. A general expression for the height required by gravity separation, diameter and velocity of those droplets carried over was also obtained. In the analysis, the slip between two phases was considered and a combined term of diameter and viscosity was introduced. The modelling can provide a theoretical basis for determining the height of the gravity separation space. (2 refs., 2 figs.)

Adolescent idiopathic scoliosis in twins: a population-based survey

DEFF Research Database (Denmark)

Andersen, Mikkel O; Thomsen, Karsten; Kyvik, Kirsten O

2007-01-01

STUDY DESIGN: A questionnaire-based identification of adolescent idiopathic scoliosis (AIS) patients in a twin cohort. OBJECTIVE: The purpose of this study was to establish a scoliosis twin cohort to provide data on the heritability of AIS. SUMMARY OF BACKGROUND DATA: The etiology of AIS is still...... environmental factors. METHODS: All 46,418 twins registered in the Danish Twin Registry born from 1931 to 1982 were sent a questionnaire, which included questions about scoliosis. A total of 34,944 (75.3%) representing 23,204 pairs returned the questionnaire. RESULTS: A subgroup of 220 subjects considered...... of monozygotic and dizygotic pairs was significantly different (P scoliosis in 1 twin whose other twin has scoliosis is smaller than believed up until now....

Prevention of preterm delivery in twin pregnancy

DEFF Research Database (Denmark)

Rode, Line; Tabor, Ann

2014-01-01

The incidence of twin gestation has increased markedly over the past decades, mostly because of increased use of assisted reproductive technologies. Twin pregnancies are at increased risk of preterm delivery (i.e. birth before 37 weeks of gestation). Multiple gestations therefore account for 2...... sequelae such as abnormal neurophysiological development in early childhood and underachievement in school. Several treatment modalities have been proposed in singleton high-risk pregnancies. The mechanism of initiating labour may, however, be different in singleton and twin gestations. Therefore......, it is mandatory to evaluate the proposed treatments in randomised trials of multiple gestations. In this chapter, we describe the results of trials to prevent preterm delivery in twin pregnancies....

Ferromagnetic and twin domains in LCMO manganites

International Nuclear Information System (INIS)

Jung, G.; Markovich, V.; Mogilyanski, D.; Beek, C. van der; Mukovskii, Y.M.

2005-01-01

Ferromagnetic and twin domains in lightly Ca-doped La 1-x Ca x MnO 3 single crystals have been visualized and investigated by means of the magneto-optical technique. Both types of domains became visible below the Curie temperature. The dominant structures seen in applied magnetic field are associated with magneto-crystalline anisotropy and twin domains. In a marked difference to the twin domains which appear only in applied magnetic field, ferromagnetic domains show up in zero applied field and are characterized by oppositely oriented spontaneous magnetization in adjacent domains. Ferromagnetic domains take form of almost periodic, corrugated strip-like structures. The corrugation of the ferromagnetic domain pattern is enforced by the underlying twin domains

Conjoined twins: morphogenesis of the heart and a review.

Science.gov (United States)

Gilbert-Barness, Enid; Debich-Spicer, Diane; Opitz, John M

2003-08-01

Five cases of conjoined twins have been studied. These included three thoracopagus twins, one monocephalus diprosopus (prosop = face), and one dicephalus dipus dibrachus. The thoracopagus twins were conjoined only from the upper thorax to the umbilicus with a normal foregut. These three cases shared a single complex multiventricular heart, one with a four chambered heart with one atrium and one ventricle belonging to each twin with complex venous and arterial connection; two had a seven chambered heart with four atria and three ventricles. The mono-cephalus diprosopus twins had a single heart with tetralogy of Fallot. The dicephalus twins had two separate axial skeletons to the sacrum, two separate hearts were connected between the right atria with a shared inferior vena cava. Thoracopagus twinning is associated with complex cardiac malformations. The cardiac anlagen in cephalopagus or diprosopus are diverted and divided along with the entire rostral end of the embryonic disc and result in two relatively normal shared hearts. However, in thoracopagus twins the single heart is multiventricular and suggests very early union with fusion of the cardiac anlagen before significant differentiation. Cardiac morphogenesis in conjoined twins therefore appears to depend on the site of the conjoined fusion and the temporal and spatial influence that determines morphogenesis as well as abnormally oriented embryonic axes. Copyright 2003 Wiley-Liss, Inc.

[Twin pregnancy as the risk factor for neonatal intraventricular hemorrhage].

Science.gov (United States)

Wieczorek, Aleksandra I; Krasomski, Grzegorz

2015-02-01

The aim of this study was to find the perinatal risk factors of intravenricular hemorrhage in twin neonates. A retrospective analysis of 203 twin pregnancies and deliveries between 2003 and 2009 was performed. Then data according birth state and neonatal complications in 406 twins were analyzed. Twin outcome was compared with the outcome of 105 singletons born at the same time and at the same gestational age as twins. Intraventricular hemorrhage was diagnosed in 116/406 (29%) of twins. IVH was found two times more often in the analyzed group than in singletons born at the same gestational age (29% vs. 18%, p = 0,03). In 96% I and II grade hemorrhage was diagnosed and in 4% III and IV grade hemorrhage in the Papille scale was found. 1) Intraventricular hemorrhage is found more often in twins than in singleton neonates born at the same gestational age. 2) IVH in twins correlate with preterm birth and low birth weight. IVH occur more often in twins with birth weight discordance and with too small maternal weight gain.

Arterio-venous flow between monochorionic twins determined during intra-uterine transfusion

NARCIS (Netherlands)

van Gemert, Martin J. C.; van den Wijngaard, Jeroen P. H. M.; Lopriore, Enrico; Pasman, Suzanne A.; Vandenbussche, Frank P. H. A.

2008-01-01

Twin-twin transfusion syndrome (TTTS) is a severe complication of monozygotic (identical) twin fetuses sharing one single (monochorionic) placenta. TTTS is caused by a net inter-twin transfusion of blood through placental anastomoses, from one twin (the donor) to the other (the recipient), which

Undiagnosed xiphopagus twins: a perinatal malady

Directory of Open Access Journals (Sweden)

Gowri Dorairajan

2012-02-01

Full Text Available Conjoined twins are a very rare entity. It is associated with poor survival rate in the presence of vital organ sharing. The entity can be diagnosed as early as the first trimester. A conjoined twin diagnosed late in labor is a malady with high perinatal mortality and maternal morbidity. We present one such case of xiphopagus twins. The management of a case diagnosed late in labor can be very challenging. Such obstetric challenges can be avoided by a meticulous early scan with a high index of suspicion, especially in the absence of separating membrane while scanning multiple pregnancies.

The Project TALENT Twin and Sibling Study.

Science.gov (United States)

Prescott, Carol A; Achorn, Deanna Lyter; Kaiser, Ashley; Mitchell, Lindsey; McArdle, John J; Lapham, Susan J

2013-02-01

Project TALENT is a US national longitudinal study of about 377,000 individuals born in 1942-1946, first assessed in 1960. Students in about 1,200 schools participated in a 2-day battery covering aptitudes, abilities, interests, and individual and family characteristics (Flanagan, 1962; www.projectTALENT.org). Follow-up assessments 1, 5, and 11 years later assessed educational and occupational outcomes. The sample includes approximately 92,000 siblings from 40,000 families, including 2,500 twin pairs and 1,200 other siblings of twins. Until recently, almost no behavior genetic research has been conducted with the sample. In the original data collection information was not collected with the intent to link family members. Recently, we developed algorithms using names, addresses, birthdates, and information about family structure to link siblings and identify twins. We are testing several methods to determine zygosity, including use of yearbook photographs. In this paper, we summarize the design and measures in Project TALENT, describe the Twin and Sibling sample, and present our twin-sib-classmate model. In most twin and family designs, the 'shared environment' includes factors specific to the family combined with between-family differences associated with macro-level variables such as socioeconomic status. The school-based sampling design used in Project TALENT provides a unique opportunity to partition the shared environment into variation shared by siblings, specific to twins, and associated with school- and community-level factors. The availability of many measured characteristics on the family, schools, and neighborhoods enhances the ability to study the impact of specific factors on behavioral variation.

Characterization of Gastric Microbiota in Twins.

Science.gov (United States)

Dong, Quanjiang; Xin, Yongning; Wang, Lili; Meng, Xinying; Yu, Xinjuan; Lu, Linlin; Xuan, Shiying

2017-02-01

Contribution of host genetic backgrounds in the development of gastric microbiota has not been clearly defined. This study was aimed to characterize the biodiversity, structure and composition of gastric microbiota among twins. A total of four pairs of twins and eight unrelated individuals were enrolled in the study. Antral biopsies were obtained during endoscopy. The bacterial 16S rRNA gene was amplified and pyrosequenced. Sequences were analyzed for the composition, structure, and α and β diversities of gastric microbiota. Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, and Fusobacteria were the most predominant phyla of gastric microbiota. Each individual, twins as well as unrelated individuals, harbored a microbiota of distinct composition. There was no evidence of additional similarity in the richness and evenness of gastric microbiota among co-twins as compared to unrelated individuals. Calculations of θ YC and PCoA demonstrated that the structure similarity of gastric microbial community between co-twins did not increase compared to unrelated individuals. In contrast, the structure of microbiota was altered enormously by Helicobacter pylori infection. These results suggest that host genetic backgrounds had little effect in shaping the gastric microbiota. This property of gastric microbiota could facilitate the studies discerning the role of microbiota from genetic grounds in the pathogenesis.

The morphology of the sella turcica in monozygotic twins

DEFF Research Database (Denmark)

Brock-Jacobsen, Mette T; Pallisgaard, Carsten; Kjaer, Inger

2009-01-01

of 42 twin pairs (18 male and 24 female pairs, aged 18-23 years) comprised the material. Sella turcica measurements from non-twins aged 6-21 years were used as normal reference. Length, depth and diameter of the sella turcica were measured and controlled by re-measurements. Pearson's correlation...... showed that the size of the sella turcica may be partly similar and partly dissimilar within the pair of monozygotic twins. Statistical evaluation of the data showed correlations between length, depth and diameter of the sella turcica between the two twin individuals in the same twin pair. Differences...

Perinatal Mortality Among Twins In Lagos University Teaching ...

African Journals Online (AJOL)

Background: Perinatal mortality rate is reported to be higher in twins than in singletons. More than two decades ago, Abudu and Agarin reported a twinning rate of 21.1/1000 maternities and perinatal mortality rate of 142.6/1000 among twins in Lagos. Objective: To determine the current perinatal mortality rate and risk factors ...

Infantile Perineal Protrusion in Two Monochorionic Twins

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Paola Cavicchioli

2014-11-01

Full Text Available Case Report - Two female monochorionic-monoamniotic twins showed the same kind of infantile perineal protrusion (IPP at birth. Lesions in both twins progressively healed until resolution in 6 weeks' time; none of the twins have manifested, till date, alvus disturbances. Discussion and Literature Review - A literature review numbers approximately 100 reports of IPP. This condition has been classically classified into three categories: congenital/familiar (i.e., female sex, positive parental history of IPP, acquired (mainly due to constipation, and associated with lichen sclerosus et atrophicus. Conclusions and Final Remarks - This case report describes, for the first time, the presence of IPP in monochorionic-monoamniotic twins, supporting the existence of hereditary/genetic factors in the developing of this condition.

Emergency separation of a xipho-omphalopagus twin in a developing country

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Shukla R

2010-01-01

Full Text Available Female conjoined twins (thoraco-omphalopagus were delivered by emergency caesarean section in a private nursing home. On examination, one of the twins was dead and was threatening the survival of the surviving twin (twin A. An emergency separation was performed to salvage the surviving twin.

Artificial Gravity with Ergometric Exercise Training Improves Cardiovascular Function in Ambulatory Men

Science.gov (United States)

Sun, Xi-Qing; Zhu, Chao; Shang, Shu; Yao, Yong-Jie

2008-06-01

The necessity of preventing physiological deconditioning in astronauts exposed to long-term space flights is well known. Artificial gravity training via short-arm centrifugation as a countermeasure to microgravity has been considered for many years. However, an optimal duration, level and rate of exposure to artificial gravity have not yet been determined. The purpose of the present study was to investigate the cardiovascular effects of three weeks of intermittent artificial gravity with ergometric exercise training on normal ambulatory men. During 3 weeks experiment, eight healthy male subjects received alternate +1 to +2 Gz (at the foot) short-arm centrifuge training with 30 W ergometric exercise for 30 min per day. Cardiac function, heart rate variability, heart rate and blood pressure were measured before and after training. Stroke volume and total peripheral resistance increased significantly after 3 weeks training, compared with the pre-training baseline. Left ventricular ejection time (LVET) and ejection fraction increased significantly after 3 weeks training, while heart rate, the ratio of pre-ejection period to LVET, and the ratio of low frequency to high frequency power decreased significantly after 3 weeks training. These results suggest that three weeks short-arm centrifuge training with ergometric exercise could improve human cardiac systolic and pumping functions, and increase cardiac vagal modulation.

Soft-sensing model of temperature for aluminum reduction cell on improved twin support vector regression

Science.gov (United States)

Li, Tao

2018-06-01

The complexity of aluminum electrolysis process leads the temperature for aluminum reduction cells hard to measure directly. However, temperature is the control center of aluminum production. To solve this problem, combining some aluminum plant's practice data, this paper presents a Soft-sensing model of temperature for aluminum electrolysis process on Improved Twin Support Vector Regression (ITSVR). ITSVR eliminates the slow learning speed of Support Vector Regression (SVR) and the over-fit risk of Twin Support Vector Regression (TSVR) by introducing a regularization term into the objective function of TSVR, which ensures the structural risk minimization principle and lower computational complexity. Finally, the model with some other parameters as auxiliary variable, predicts the temperature by ITSVR. The simulation result shows Soft-sensing model based on ITSVR has short time-consuming and better generalization.

Anaesthesia for the separation of conjoined twins

Directory of Open Access Journals (Sweden)

Jaya Lalwani

2011-01-01

Full Text Available Thoraco-omphalopagus is one of the most common type of conjoint twins accounting for 74% cases of conjoint twins. We report the anaesthetic management for successful separation of thoraco-omphalopagus conjoint twins, both of them surviving till date. We highlight the responsibility of anaesthesia team in anaesthetising the two individual patients simultaneously, need of careful monitoring and anticipation of complications like massive blood loss, hypotension, hypokalemia, hypoxia and hypercabia. Detailed description of successful management is reported.

Detwinning mechanisms for growth twins in face-centered cubic metals

Energy Technology Data Exchange (ETDEWEB)

Wang, J., E-mail: wangj6@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Li, N.; Anderoglu, O. [Department of Mechanical Engineering, Materials Science and Engineering Program, Texas A and M University, College Station, TX 77843-3123 (United States); Zhang, X., E-mail: zhangx@tamu.edu [Department of Mechanical Engineering, Materials Science and Engineering Program, Texas A and M University, College Station, TX 77843-3123 (United States); Misra, A. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Huang, J.Y. [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Hirth, J.P. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2010-04-15

Using in situ transmission electron microscopy, we studied the stability of growth twins. We observed the rapid migration of incoherent twin boundaries (ITBs), indicating that nanotwins are unstable. Topological analysis and atomistic simulations are adopted to explore detwinning mechanisms. The results show that: (i) the detwinning process is accomplished via the collective glide of multiple twinning dislocations that form an ITB; (ii) detwinning can easily occur for thin twins, and the driving force is mainly attributed to a variation of the excess energy of a coherent twin boundary; (iii) shear stresses enable ITBs to migrate easily, causing the motion of coherent twin boundaries; and (iv) the migration velocity depends on stacking fault energy. The results imply that detwinning becomes the dominant deformation mechanism for growth twins of the order of a few nanometers thick.

Relativistic twins or sextuplets?

International Nuclear Information System (INIS)

Sheldon, Eric

2003-01-01

A recent study of the relativistic twin 'paradox' by Soni in this journal affirmed that 'A simple solution of the twin paradox also shows anomalous behaviour of rigidly connected distant clocks' but entailed a pedagogic hurdle which the present treatment aims to surmount. Two scenarios are presented: the first 'flight-plan' is akin to that depicted by Soni, with constant-velocity segments, while the second portrays an alternative mission undertaken with sustained acceleration and deceleration, illustrated quantitatively for a two-way spacecraft flight from Earth to Polaris (465.9 light years distant) and back

Relativistic twins or sextuplets?

CERN Document Server

Sheldon, E S

2003-01-01

A recent study of the relativistic twin 'paradox' by Soni in this journal affirmed that 'A simple solution of the twin paradox also shows anomalous behaviour of rigidly connected distant clocks' but entailed a pedagogic hurdle which the present treatment aims to surmount. Two scenarios are presented: the first 'flight-plan' is akin to that depicted by Soni, with constant-velocity segments, while the second portrays an alternative mission undertaken with sustained acceleration and deceleration, illustrated quantitatively for a two-way spacecraft flight from Earth to Polaris (465.9 light years distant) and back.

Risk of Oral Clefts in Twins

DEFF Research Database (Denmark)

Grosen, Dorthe; Bille, Camilla; Petersen, Inge

2011-01-01

and heritability. Twins (207 affected/130,710) and singletons (7766 affected/4,798,526) born from 1936 through 2004 in Denmark were ascertained by linkage among the Danish Facial Cleft Database, the Danish Twin Registry, and the Civil Registration System. We computed oral cleft prevalence and prevalence proportion...

Coffee and smoking as risk factors of twin pregnancies

DEFF Research Database (Denmark)

Morales-Suárez-Varela, Maria M; Bech, Bodil Hammer; Christensen, Kaare

2007-01-01

their prepregnancy weight and height, coffee and alcohol intake, smoking habits, and potential confounding factors at early stages of pregnancy. We identified smoking (> 10 cigarettes/day) as a possible determinant of twinning, particularly for dizygotic twinning rates (same sex) and furthermore corroborated......Twinning rates have changed substantially over time for reasons that are only partly known. In this study we studied smoking, coffee and alcohol intake, and their possible interaction with obesity as potential determinants of twinning rates using data from the Danish National Birth Cohort between...... 1996 and 2002. We identified 82,985 pregnancies: 81,954 singleton and 1031 twins. For the twins we had data to classify 121 as monozygotic, 189 dizygotic (same sex), 313 dizygotic (opposite sex) but, 408 were of the same sex but with unknown zygosity. All mothers were interviewed about...

[Early prenatal diagnosis of diprosopic syncephalic joined twins].

Science.gov (United States)

Picaud, A; Nlome-Nze, A R; Engongha-Beka, T; Ogowet-Igumu, N

1990-06-01

The authors summarize the case of diprosopic syncephalic joined twins diagnosed at 22 weeks of pregnancy by ultrasonography performed because of hydramnios. The rate of separation anomalies of monozygotic twins is assessed by a review of the literature: from 1 to twenty to fifty thousands for joined twins to 1 per cent fifty thousand to fifteen millions for diprosopus. The etiology is the result of a late division of the egg between D12 and D16. Often an encephalic diprosopic joined twins cause elevated levels of maternal serum alpha protein. Early ultrasonography permits to consider a vaginal therapeutic abortion.

Imperfect twinning: a clinical and ethical dilemma.

Science.gov (United States)

Denardin, Daniela; Telles, Jorge Alberto B; Betat, Rosilene da Silveira; Fell, Paulo Renato K; Cunha, André Campos da; Targa, Luciano Vieira; Zen, Paulo Ricardo G; Rosa, Rafael Fabiano M

2013-09-01

OBJECTIVE To review the history, epidemiology, etiology, gestational aspects, diagnosis and prognosis of imperfect twinning. DATA SOURCES Scientific articles were searched in PubMed, SciELO and Lilacs databases, using the descriptors "conjoined twins", "multiple pregnancy", "ultrasound", "magnetic resonance imaging" and "prognosis". The research was not delimited to a specific period of time and was supplemented with bibliographic data from books. The description of conjoined twins is legendary. The estimated frequency is 1/45,000-200,000 births. These twins are monozygotic, monochorionic and usually monoamniotic. They can be classified by the most prominent fusion site, by the symmetry between the conjoined twins or by the sharing structure. The diagnosis can be performed in the prenatal period or after birth by different techniques, such as ultrasound, magnetic resonance imaging and echocardiography. These tests are of paramount importance for understanding the anatomy of both fetuses/children, as well as for prognosis and surgical plan determination. CONCLUSIONS Although imperfect twinning is a rare condition, the prenatal diagnosis is very important in order to evaluate the fusion site and its complexity. Hence, the evaluation of these children should be multidisciplinary, involving mainly obstetricians, pediatricians and pediatric surgeons. However, some decisions may constitute real ethical dilemmas, in which different points should be discussed and analyzed with the health team and the family.

Twin Delivery: Comparison of Incidence and Foetal Outcome in two ...

African Journals Online (AJOL)

Background: The incidence of twin delivery in Nigeria may have changed, in view of the worldwide increase in the rates of twinning attributed to increasing maternal age and use of fertility therapies. Objective: To determine the current incidence of twin delivery in Benin City and document the foetal outcome in twins.

Conjoined twins detected in the first trimester: A review

Directory of Open Access Journals (Sweden)

Chih-Ping Chen

2011-12-01

Full Text Available Conjoined twinning occurs in 1 in 100 sets of monozygotic twins, 1 in 50,000 gestations or 1 in 250,000 live births. With the advent of ultrasound technology, prenatal diagnosis of conjoined twins is possible. This article provides a comprehensive review of conjoined twins detected in the first trimester including fetal gender, maternal age, parity, types of fusion, related ultrasound abnormalities, perinatal outcome and association with assisted reproduction.

Heredity In Sarcoidosis - A Registry-Based Twin Study

DEFF Research Database (Denmark)

Sverrild, Asger; Backer, Vibeke; Kyvik, Kirsten Ohm

2008-01-01

BACKGROUND: Sarcoidosis is a multiorgan, granulomatous, inflammatory disease with unknown aetiology. Familial clustering of cases and ethnic variation in the epidemiology suggests a genetic influence on the disease susceptibility. AIM: This paper reports twin concordance and heritability estimates...... of sarcoidosis in order to assess the overall contribution of genetic factors to the disease susceptibility. METHODS: Monozygotic and dizygotic twins enrolled in either the Danish or the Finnish population-based, national Twin Cohorts (61,662 pairs in total) were linked to diagnostic information on sarcoidosis.......012. Compared to the general population we found an 80-fold increased risk of developing sarcoidosis in co-twins of affected monozygotic brothers or sisters. The increased risk in dizygotic twins was on the other hand only 7-fold. Aetiological model fitting gave a heritability of sarcoidosis of 0.66 (95% CI 0...

Nike Twins Seven Seven: Nigerian Batik Artist.

Science.gov (United States)

LaDuke, Betty

1987-01-01

Chronicles the personal and professional life of Nike Twins Seven Seven (born 1951), a Nigerian batik artist, and her husband, Twins Seven Seven, a musician-artist, both of whom have received international acclaim. (BJV)

Secular trends in gestational age and birthweight in twins.

Science.gov (United States)

Gielen, M; van Beijsterveldt, C E M; Derom, C; Vlietinck, R; Nijhuis, J G; Zeegers, M P A; Boomsma, D I

2010-09-01

In recent decades, the overall rate of preterm births has increased. The aim of the present study was to examine whether this trend is also seen for multiple gestations. More specifically, we examined if there has been a decrease in gestational age for live born monozygotic (MZ) and dizygotic (DZ) twins and if there has been a simultaneous change in birthweight. The contributions of fertility treatments and Caesarean sections were taken into consideration. All analyses were carried out in two large European twin cohorts. Cross-sectional study of 6310 live born twin pairs, born between 1964-2007, from the Belgian East Flanders Prospective Twin Survey and 14,712 twin pairs, born between 1990-2006, from the Netherlands Twin Register. Multiple regression analyses were performed with gestational age as outcome variable, and multilevel analysis with birthweight as outcome variable. All analyses were performed with and without adjustment for zygosity, parity, maternal age, mode of conception and delivery and, for the analyses of birthweight, gestational age. Gestational age decreased in a linear fashion from 1964 to 2007 with a decrease of 0.25 days per year in a similar way for MZ and DZ twins. Changes in birthweight depended on gestational age: up to 32 weeks, birthweight decreased and after 32 weeks birthweight increased. The frequency of infertility treatment and Caesarean sections, primiparity and advanced maternal age increased over the years, but none of these factors influenced the secular trends in gestational age and birthweight. The decrease in gestational age and change in birthweight in twins are sources of concern, especially for very preterm twins, for whom birthweight decreased. For twins born after 32 weeks, an increase in birthweight was observed and this is very likely the explanation for the decrease in gestational age.

Characterization of the matrix-twin interface of a (1 0 -1 2) twin during growth

Czech Academy of Sciences Publication Activity Database

Ostapovets, Andriy; Serra, A.

2014-01-01

Roč. 94, č. 25 (2014), s. 2827-2839 ISSN 1478-6443 R&D Projects: GA MŠk(CZ) EE2.3.30.0063 Grant - others:Catalan Government(ES) AGAUR2014SGR 1644; Spanish Secretariat of Research, Development and Innovation(ES) FIS2012-39433-C02-02 Institutional support: RVO:68081723 Keywords : twinning * twin boundaries * disconnections Subject RIV: BM - Solid Matter Physics ; Magnetism; BM - Solid Matter Physics ; Magnetism (FZU-D)

Even-dimensional topological gravity from Chern-Simons gravity

International Nuclear Information System (INIS)

Merino, N.; Perez, A.; Salgado, P.

2009-01-01

It is shown that the topological action for gravity in 2n-dimensions can be obtained from the (2n+1)-dimensional Chern-Simons gravity genuinely invariant under the Poincare group. The 2n-dimensional topological gravity is described by the dynamics of the boundary of a (2n+1)-dimensional Chern-Simons gravity theory with suitable boundary conditions. The field φ a , which is necessary to construct this type of topological gravity in even dimensions, is identified with the coset field associated with the non-linear realizations of the Poincare group ISO(d-1,1).

Upgrades for TwinSol facility

Energy Technology Data Exchange (ETDEWEB)

O’Malley, P.D.; Bardayan, D.W.; Kolata, J.J.; Hall, M.R.; Hall, O.; Allen, J. [Physics Department, University of Notre Dame, Notre Dame, IN 46556 (United States); Becchetti, F.D. [Physics Department, U. Michigan, Ann Arbor MI 48109 (United States)

2016-06-01

TwinSol, a pair of coupled, superconducting solenoids, was one of the first devices capable of producing beams of radioactive nuclei at energies near the Coulomb barrier. A primary beam from University of Notre Dame (UND) tandem accelerator is used to bombard a primary target producing a secondary beam in flight. TwinSol is used to gather, separate, and focus the recoils. Since it was commissioned at the UND in 1997, at least 58 publications have reported data from its use and there have been hundreds of collaborators from many different countries that use this device. Currently, plans are in place at the UND to provide several upgrades to TwinSol, including a multi-cell gas production target and the possible addition of a third solenoid. Upgrades currently in progress will be discussed along with future plans.

Quantum spreading of a self-gravitating wave-packet in singularity free gravity

Science.gov (United States)

Buoninfante, Luca; Lambiase, Gaetano; Mazumdar, Anupam

2018-01-01

In this paper we will study for the first time how the wave-packet of a self-gravitating meso-scopic system spreads in theories beyond Einstein's general relativity. In particular, we will consider a ghost-free infinite derivative gravity, which resolves the 1 / r singularity in the potential - such that the gradient of the potential vanishes within the scale of non-locality. We will show that a quantum wave-packet spreads faster for a ghost-free and singularity-free gravity as compared to the Newtonian case, therefore providing us a unique scenario for testing classical and quantum properties of short-distance gravity in a laboratory in the near future.

Spectral dimension of the universe in quantum gravity at a lifshitz point.

Science.gov (United States)

Horava, Petr

2009-04-24

We extend the definition of "spectral dimension" d_{s} (usually defined for fractal and lattice geometries) to theories in spacetimes with anisotropic scaling. We show that in gravity with dynamical critical exponent z in D+1 dimensions, the spectral dimension of spacetime is d_{s}=1+D/z. In the case of gravity in 3+1 dimensions with z=3 in the UV which flows to z=1 in the IR, the spectral dimension changes from d_{s}=4 at large scales to d_{s}=2 at short distances. Remarkably, this is the behavior found numerically by Ambjørn et al. in their causal dynamical triangulations approach to quantum gravity.

Age versus size determination of radial variation in wood specific gravity : lessons from eccentrics

Science.gov (United States)

G. Bruce Williamson; Michael C. Wiemann

2011-01-01

Radial increases in wood specific gravity have been shown to characterize early successional trees from tropical forests. Here, we develop and apply a novel method to test whether radial increases are determined by tree age or tree size. The method compares the slopes of specific gravity changes across a short radius and a long radius of trees with eccentric trunks. If...

Phase field modeling of twinning in indentation of transparent crystals

International Nuclear Information System (INIS)

Clayton, J D; Knap, J

2011-01-01

Continuum phase field theory is applied to study elastic twinning in calcite and sapphire single crystals subjected to indentation loading by wedge-shaped indenters. An order parameter is associated with the magnitude of stress-free twinning shear. Geometrically linear and nonlinear theories are implemented and compared, the latter incorporating neo-Hookean elasticity. Equilibrium configurations of deformed and twinned crystals are attained numerically via direct energy minimization. Results are in qualitative agreement with experimental observations: a long thin twin forms asymmetrically under one side of the indenter, the tip of the twin is sharp and the length of the twin increases with increasing load. Qualitatively similar results are obtained using isotropic and anisotropic elastic constants, though the difference between isotropic and anisotropic results is greater in sapphire than in calcite. Similar results are also obtained for nanometer-scale specimens and millimeter-scale specimens. Indentation forces are greater in the nonlinear model than the linear model because of the increasing tangent bulk modulus with increasing pressure in the former. Normalized relationships between twin length and indentation force are similar for linear and nonlinear theories at both nanometer and millimeter scales. Twin morphologies are similar for linear and nonlinear theories for indentation with a 90° wedge. However, in the nonlinear model, indentation with a 120° wedge produces a lamellar twin structure between the indenter and the long sharp primary twin. This complex microstructure is not predicted by the linear theory

Favourable effect of TNF-alpha inhibitor (infliximab) on Blau syndrome in monozygotic twins with a de novo CARD15 mutation

DEFF Research Database (Denmark)

Milman, Nils; Andersen, Claus B; Hansen, Annette

2006-01-01

Blau syndrome is a hereditary granulomatous disease caused by mutations in the CARD15 gene that is diagnosed in children of young age with exanthema/erythema, arthritis/periarthritis and/or uveitis. We report two cases of Blau syndrome in Danish Caucasian monozygotic male twins, exhibiting...... a heterozygous de novo R334W mutation in codon 334 of CARD15. The patients were initially diagnosed as having sarcoidosis. In both twins, symptoms (exanthema, arthritis/periarthritis) started at 1 year of age, and were followed by uveitis at 7-10 years of age. There was no involvement of the lungs or other...... quality of life. At follow up at 20 years of age (after 2-5 years of infliximab treatment) the twins had an almost normal physical appearance and a normal psychomotoric development, indicating a favourable short-term prognosis of the disease. Blau syndrome has pathologic, clinical and therapeutic features...

Fatique life and twinning in alphazirconium

DEFF Research Database (Denmark)

Warren, M.R.; Beevers, C.J.

1970-01-01

stress for {11−21} twinning of ~0.5 kg mm−2 in zirconium containing 0.003 wt pct O. During observations confined to internal grains it was found that increasing grain size and decreasing oxygen content favored the formation of fatigue damage in association with these {11−21} twins. In external grains...

Twin and grain boundary in InP: A synchrotron radiation study

International Nuclear Information System (INIS)

Han, Y.; Liu, X.; Jiao, J.; Lin, L.; Jiang, J.; Wang, Z.; Tian, Y.

1998-01-01

Experimentally observed X-ray reflectivity curves show bi-crystal(twin) characteristics. The study revealed that there was defect segregation at the twin boundary. Stress was relaxed at the edge of the boundary. Relaxation of the stress resulted in formation of twin and other defects. As a result of formation of such defects, a defect-free and stress-free zone or low defect density and small stress zone is created around the defects. So a twin model was proposed to explain the experimental results. Stress(mainly thermal stress), chemical stoichiometry deviation and impurities nonhomogeneous distributions are the key factors that cause twins in LEC InP crystal growth. Twins on (111) face in LEC InP crystal were studied. Experimental evidence of above mentioned twin model and suggestions on how to get twin-free LEC InP single crystals will be discussed

Diabetes and perinatal mortality in twin pregnancies.

Directory of Open Access Journals (Sweden)

Zhong-Cheng Luo

Full Text Available BACKGROUND: Diabetes in pregnancy has been associated with a paradoxically reduced risk of neonatal death in twin pregnancies. Risk "shift" may be a concern in that the reduction in neonatal deaths may be due to an increase in fetal deaths (stillbirths. This study aimed to clarify the impact of diabetes on the risk of perinatal death (neonatal death plus stillbirth in twin pregnancies. METHODS: This was a retrospective cohort study of twin births using the largest available dataset on twin births (the U.S. matched multiple birth data 1995-2000; 19,676 neonates from diabetic pregnancies, 541,481 from non-diabetic pregnancies. Cox proportional hazard models were applied to estimate the adjusted hazard ratios (aHR of perinatal death accounting for twin cluster-level dependence. RESULTS: Comparing diabetic versus non-diabetic twin pregnancies, overall perinatal mortality rate was counterintuitively lower [2.1% versus 3.3%, aHR 0.70 (95% confidence intervals 0.63-0.78]. Individually, both stillbirth and neonatal mortality rates were lower in diabetic pregnancies, but we identified significant differences by gestational age and birth weight. Diabetes was associated with a survival benefit in pregnancies completed before 32 weeks [aHR 0.55 (0.48-0.63] or with birth weight =2500 g [aHR 2.20 (1.55-3.13]. CONCLUSIONS: Diabetes in pregnancy appears to be "protective" against perinatal death in twin pregnancies ending in very preterm or very low birth weight births. Prospective studies are required to clarify whether these patterns of risk are real, or they are artifacts of unmeasured confounders. Additional data correlating these outcomes with the types of diabetes in pregnancy are also needed to distinguish the effects of pre-gestational vs. gestational diabetes.

Detection of chromosomal abnormalities, congenital abnormalities and transfusion syndrome in twins

DEFF Research Database (Denmark)

Sperling, L.; Kiil, C.; Larsen, Lene Unmack

2007-01-01

OBJECTIVE: To evaluate the outcome of screening for structural malformations in twins and the outcome of screening for twin-twin transfusion syndrome (TTTS) among monochorionic twins through a number of ultrasound scans from 12 weeks' gestation. METHODS: Enrolled into this prospective multicenter...... by assisted reproduction. The incidence of TTTS was 23% from 12 weeks until delivery, and all those monochorionic twin pregnancies that miscarried had signs of TTTS. CONCLUSION: Twin pregnancies have an increased risk of congenital malformations and one out of four monochorionic pregnancies develops TTTS....... Ultrasound screening to assess chorionicity and follow-up of monochorionic pregnancies to detect signs of TTTS, as well as malformation screening, are therefore essential in the antenatal care of twin pregnancies....

Emergency separation of a xipho-omphalopagus twin in a ...

African Journals Online (AJOL)

Emergency separation of a xipho-omphalopagus twin in a developing country. RM Shukla, B Mukhopadhyay, KC Mandal, K Saha, D Roy, PP Mukherjee. Abstract. Female conjoined twins (thoraco-omphalopagus) were delivered by emergency caesarean section in a private nursing home. On examination, one of the twins ...

Obstetric outcome of twin pregnancies in Jos, Nigeria | Mutihir ...

African Journals Online (AJOL)

Obstetric outcome of twin pregnancies in Jos, Nigeria. JT Mutihir, VC Pam. Abstract. Objectives: The objectives of the study were to determine the incidence, maternal and foetal outcome of twin delivery in Jos, Nigeria. Methodology: All consecutive twin deliveries between August 2003 and November 2004 were studied.

Prenatal diagnosis of chorionicity in twins.

LENUS (Irish Health Repository)

Hassan, T

2012-02-01

The aim of this audit was to assess the accuracy of transabdominal ultrasound scan in predicting chorionicity in twin pregnancies in our unit. The presence or absence of lambda sign, T-sign, dividing membrane thickness and number of placentae were used to determine chorionicity. We retrospectively analysed these antenatal markers in 268 sets of twins delivered over a 5 year period and compared it with the postpartum placental histology and neonatal gender. Of 268 twin deliveries, 204 (76%) had both chorionicity and placental histology to compare. 67 of 84 (80%) were correctly diagnosed antenatally as monochorionic and 137 of 151 (91%) as dichorionic. In 31 cases (15%) the ultrasound diagnosis of chorionicity didn\\'t match placental histology. Seventeen were thought to be monochorionic antenatally but were confirmed dichorionic on placental histology. Overall chorionicity was correctly diagnosed in 171\\/204 (84%) using transabdominal ultrasound scan (USS) in all trimesters. However the sensitivity and specificity of USS was much higher for dichorionic twins when carried out before 14 weeks of gestation.

Yoruba customs and beliefs pertaining to twins.

Science.gov (United States)

Leroy, Fernand; Olaleye-Oruene, Taiwo; Koeppen-Schomerus, Gesina; Bryan, Elizabeth

2002-04-01

The Yoruba are an important ethnic group mainly occupying Southwestern Nigeria. Mainly for genetic reasons, this very large tribe happens to present the highest dizygotic twinning rate in the world (4.4 % of all maternities). The high perinatal mortality rate associated with such pregnancies has contributed to the integration of a special twin belief system within the African traditional religion of this tribe. The latter is based on the concept of a supreme deity called Olodumare or Olorun, assisted by a series of secondary gods (Orisha) while Yoruba religion also involves immortality and reincarnation of the soul based on the animistic cult of ancestors. Twins are therefore given special names and believed to detain special preternatural powers. In keeping with their refined artistic tradition, the Yoruba have produced numerous wooden statuettes called Ibejis that represent the souls of deceased newborn twins and are involved in elaborate rituals. Among Yoruba traditional beliefs and lore some twin-related themes are represented which are also found in other parts of the world. Basic features of the original Yoruba beliefs have found their way into the religious traditions of descendants of African slaves imported in the West Indies and in South America.

Reciprocal Longitudinal Associations Between Adolescent Twin Gambling and Delinquency.

Science.gov (United States)

Vitaro, Frank; C Hartl, Amy; Laursen, Brett; Brendgen, Mara; Dionne, Ginette; Boivin, Michel

2015-12-01

This study examined sibling influence over gambling involvement and delinquency in a sample of 628 twins (151 male dyads, 163 female dyads). Self-reports of gambling involvement and delinquency were collected for each twin at ages 13, 14 and 15 years. Results revealed evidence of between-twin influence. Higher levels of an adolescent's delinquency predicted an increase in his or her co-twin's delinquency from age 13 to age 14 and from age 14 to age 15. In contrast, gambling behavior was unaffected by the co-twin's gambling involvement. Within-twins, higher initial levels of delinquency predicted a subsequent increase in gambling behavior from age 13 to age 14 and again from age 14 to age 15, and higher initial levels of gambling involvement predicted an increase in delinquency from age 14 to age 15. Between and within siblings effects are discussed in light of the scant literature on (a) sibling influence on gambling, and (b) the links between gambling and delinquency.

Twin Rotating Coils for Cold Magnetic Measurements of 15 m Long LHC Dipoles

CERN Document Server

Billan, J; Buzio, M; D'Angelo, G; Deferne, G; Dunkel, O; Legrand, P; Rijllart, A; Siemko, A; Sievers, P; Schloss, S; Walckiers, L

2000-01-01

We describe here a new harmonic coil system for the field measurement of the superconducting, twin aperture LHC dipoles and the associated corrector magnets. Besides field measurements the system can be used as an antenna to localize the quench origin. The main component is a 16 m long rotating shaft, made up of 13 ceramic segments, each carrying two tangential coils plus a central radial coil, all working in parallel. The segments are connected with flexible Ti-alloy bellows, allowing the piecewise straight shaft to follow the curvature of the dipole while maintaining high torsional rigidity. At each interconnection the structure is supported by rollers and ball bearings, necessary for the axial movement for installation and for the rotation of the coil during measurement. Two such shafts are simultaneously driven by a twin-rotating unit, thus measuring both apertures of a dipole at the same time. This arrangement allows very short measurement times (typically 10 s) and is essential to perform cold magnetic ...

Strong crystal size effect on deformation twinning

DEFF Research Database (Denmark)

Yu, Qian; Shan, Zhi-Wei; Li, Ju

2010-01-01

plasticity. Accompanying the transition in deformation mechanism, the maximum flow stress of the submicrometre-sized pillars was observed to saturate at a value close to titanium’s ideal strength9, 10. We develop a ‘stimulated slip’ model to explain the strong size dependence of deformation twinning......Deformation twinning1, 2, 3, 4, 5, 6 in crystals is a highly coherent inelastic shearing process that controls the mechanical behaviour of many materials, but its origin and spatio-temporal features are shrouded in mystery. Using micro-compression and in situ nano-compression experiments, here we...... find that the stress required for deformation twinning increases drastically with decreasing sample size of a titanium alloy single crystal7, 8, until the sample size is reduced to one micrometre, below which the deformation twinning is entirely replaced by less correlated, ordinary dislocation...

Imaging of conjoined twins

Energy Technology Data Exchange (ETDEWEB)

McHugh, Kieran [Great Ormond Street Hospital for Children, Department of Radiology, London (United Kingdom); Kiely, Edward M.; Spitz, Lewis [Great Ormond Street Hospital for Children, Department of Surgery, London (United Kingdom)

2006-09-15

The incidence of conjoined twins is estimated to be around 1 in 250,000 live births. There is a distinct female predominance. In this paper the imaging of conjoined twins both antenatally and postnatally is reviewed, in particular taking into consideration recent advances with multidetector CT. Accurate counselling of parents regarding the likely outcome of the pregnancy and the likelihood of successful separation is dependent on good prenatal imaging with ultrasound and MRI. Planning of postnatal surgical separation is aided by accurate preoperative imaging which, depending on the conjoined area, will encompass many imaging modalities, but often relies heavily on CT scanning. (orig.)

Imaging of conjoined twins

International Nuclear Information System (INIS)

McHugh, Kieran; Kiely, Edward M.; Spitz, Lewis

2006-01-01

The incidence of conjoined twins is estimated to be around 1 in 250,000 live births. There is a distinct female predominance. In this paper the imaging of conjoined twins both antenatally and postnatally is reviewed, in particular taking into consideration recent advances with multidetector CT. Accurate counselling of parents regarding the likely outcome of the pregnancy and the likelihood of successful separation is dependent on good prenatal imaging with ultrasound and MRI. Planning of postnatal surgical separation is aided by accurate preoperative imaging which, depending on the conjoined area, will encompass many imaging modalities, but often relies heavily on CT scanning. (orig.)

Polar gravity fields from GOCE and airborne gravity

DEFF Research Database (Denmark)

Forsberg, René; Olesen, Arne Vestergaard; Yidiz, Hasan

2011-01-01

Airborne gravity, together with high-quality surface data and ocean satellite altimetric gravity, may supplement GOCE to make consistent, accurate high resolution global gravity field models. In the polar regions, the special challenge of the GOCE polar gap make the error characteristics...... of combination models especially sensitive to the correct merging of satellite and surface data. We outline comparisons of GOCE to recent airborne gravity surveys in both the Arctic and the Antarctic. The comparison is done to new 8-month GOCE solutions, as well as to a collocation prediction from GOCE gradients...... in Antarctica. It is shown how the enhanced gravity field solutions improve the determination of ocean dynamic topography in both the Arctic and in across the Drake Passage. For the interior of Antarctica, major airborne gravity programs are currently being carried out, and there is an urgent need...

Personality, depression, and premorbid lifestyle in twin pairs discordant for Parkinson's disease

Science.gov (United States)

Heberlein, I.; Ludin, H.; Scholz, J.; Vieregge, P.

1998-01-01

Present personality traits (Freiburg personality inventory, FPI-R), depression (von Zerssen's depression scale), and self assessed state of health were evaluated in 15 twin pairs (six monozygotic and nine dizygotic; mean age 62.5 years) discordant for idiopathic Parkinson's disease and in 17 unrelated healthy control subjects. The twins had additional questionnaire based interviews on premorbid lifestyle.
For disability, twins with Parkinson's disease scored lower on FPI-R than controls in "achievement orientation" and "extraversion", higher in "inhibitedness", "somatic complaints", and "emotionality". They scored higher for depression and for state of health than unaffected twins and controls. For zygosity, monozygotic twins scored lower than dizygotic twins in "achievement orientation", "aggressiveness", and "strain". Monozygotic twins had less "achievement orientation" and "extraversion" and more "somatic complaints" than controls. Monozygotic twins had a lower within pair difference than dizygotic twins in "social orientation". During premorbid times the affected twin with later Parkinson's disease was estimated to have been "less often the leader" in the twin pair.
Although small in sample size, this twin study indicates a genetic impact for some personality features beyond the Parkinson's disease motor syndrome.

 PMID:9489545

Gaviscon and domperidon responsive apnea episodes associated with gastro-esophageal reflux disease in twins.

Science.gov (United States)

Bilgin, Huseyin; Eren, Abdulkadir; Kara, Semra

2015-01-01

The possible pathophysiology of the relationship between gastro-esophageal reflux disease and apnea of prematurity has been widely investigated. Various physiological protective reflex responses provide a plausible biological link between gastro-esophageal reflux and apnea of prematurity. It is uncertain whether or not there is a causal relationship between the two diseases. PATIENT'S FINDINGS: Twins were admitted to the neonatal intensive care unit due to feeding problems. Physical examination was normal except for reticulated, blueviolet skin changes. Short apneic attacks occurred on the first day in twin 1 and on the second day in twin 2, and these were initially treated by stimulation and increased ambient O2 concentration. Then, we conducted methylxanthine and continuous positive airway pressure treatment. Laboratory and radiological analysis were normal. As gastro-esophageal reflux disease was thought to be the causes of the treatment-refractory apnea, therapy with gaviscon and domperidon was begun for both cases. Apneic attacks did not recur after gaviscon and domperidon therapy. Pharmacological therapy for gastro-esophageal reflux disease has not definitively been shown to be effective in improving symptoms and hence, should be reserved especially for infants with treatment refractory apnea episodes suspected as being gastro-esophageal reflux in premature infants.

Arterio-venous flow between monochorionic twins determined during intra-uterine transfusion

Energy Technology Data Exchange (ETDEWEB)

Gemert, Martin J C van; Wijngaard, Jeroen P H M van den [Laser Centre and Department of Obstetrics, Laser Center, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands); Lopriore, Enrico [Division of Neonatology, Department of Pediatrics, Leiden University Medical Centre, Leiden (Netherlands); Pasman, Suzanne A; Vandenbussche, Frank P H A [Division of Fetal Medicine, Department of Obstetrics, Leiden University Medical Centre, Leiden (Netherlands)], E-mail: m.j.vangemert@amc.uva.nl

2008-04-07

Twin-twin transfusion syndrome (TTTS) is a severe complication of monozygotic (identical) twin fetuses sharing one single (monochorionic) placenta. TTTS is caused by a net inter-twin transfusion of blood through placental anastomoses, from one twin (the donor) to the other (the recipient), which link the two feto-placental circulations. Currently, the only reliable method to measure the net inter-twin transfusion clinically is when incomplete laser therapy of TTTS occurs and one of the twins becomes anemic and requires an intra-uterine transfusion of adult red blood cells. Then, differences between adult hemoglobin concentrations measured during the transfusion and at birth relate not only to the net inter-twin transfusion but also to the finite lifetime of the adult red blood cells. We have analyzed this situation, derived the differential equations of adult hemoglobin in the donor and recipient twins, given the solutions and given expressions relating the net inter-twin flow with clinically measured parameters. We have included single and multiple intra-uterine transfusions. In conclusion, because incomplete laser therapy occurs frequently, and some cases require an intra-uterine transfusion, this method may allow collecting a wealth of net inter-twin flow data from clinicians involved in laser therapy of TTTS. To aid to the widespread use of this method, we have presented the equations as clearly as possible in tables for easy use by others. (note)

Arterio-venous flow between monochorionic twins determined during intra-uterine transfusion

International Nuclear Information System (INIS)

Gemert, Martin J C van; Wijngaard, Jeroen P H M van den; Lopriore, Enrico; Pasman, Suzanne A; Vandenbussche, Frank P H A

2008-01-01

Twin-twin transfusion syndrome (TTTS) is a severe complication of monozygotic (identical) twin fetuses sharing one single (monochorionic) placenta. TTTS is caused by a net inter-twin transfusion of blood through placental anastomoses, from one twin (the donor) to the other (the recipient), which link the two feto-placental circulations. Currently, the only reliable method to measure the net inter-twin transfusion clinically is when incomplete laser therapy of TTTS occurs and one of the twins becomes anemic and requires an intra-uterine transfusion of adult red blood cells. Then, differences between adult hemoglobin concentrations measured during the transfusion and at birth relate not only to the net inter-twin transfusion but also to the finite lifetime of the adult red blood cells. We have analyzed this situation, derived the differential equations of adult hemoglobin in the donor and recipient twins, given the solutions and given expressions relating the net inter-twin flow with clinically measured parameters. We have included single and multiple intra-uterine transfusions. In conclusion, because incomplete laser therapy occurs frequently, and some cases require an intra-uterine transfusion, this method may allow collecting a wealth of net inter-twin flow data from clinicians involved in laser therapy of TTTS. To aid to the widespread use of this method, we have presented the equations as clearly as possible in tables for easy use by others. (note)

Short-range fundamental forces

International Nuclear Information System (INIS)

Antoniadis, I.; Baessler, S.; Buchner, M.; Fedorov, V.V.; Hoedl, S.; Nesvizhevsky, V.V.; Pignol, G.; Protasov, K.V.; Lambrecht, A.; Reynaud, S.; Sobolev, Y.

2010-01-01

We consider theoretical motivations to search for extra short-range fundamental forces as well as experiments constraining their parameters. The forces could be of two types: 1) spin-independent forces; 2) spin-dependent axion-like forces. Different experimental techniques are sensitive in respective ranges of characteristic distances. The techniques include measurements of gravity at short distances, searches for extra interactions on top of the Casimir force, precision atomic and neutron experiments. We focus on neutron constraints, thus the range of characteristic distances considered here corresponds to the range accessible for neutron experiments

Cancer risk in opposite-sex and same-sex twins

DEFF Research Database (Denmark)

Juel Ahrenfeldt, Linda

2015-01-01

Twin pregnancies are characterized by simultaneous development of two fetuses that share the womb. An interest in opposite-sex (OS) twins, twin pairs consisting of one male and one female, comes from animal studies that showed that exposure to sex hormones is influenced by the position of the fetus...

Influences on achieving motor milestones: A twin-singleton study

NARCIS (Netherlands)

Brouwer, S.I.; van Beijsterveldt, C.E.M.; Bartels, M.; Hudziak, J.; Boomsma, D.I.

2006-01-01

In order to determine if twinning impacted achievement of motor milestones the attainment of early motor milestones in twins was examined and compared to published data from singletons of the same age from the same culture and birth years. We examined the influence of twinning, sex, zygosity and

Gestation period and twinning in chimpanzees.

Science.gov (United States)

PEACOCK, L J; ROGERS, C M

1959-04-10

The length of the gestation period in 118 births in a colony of chimpanzees was found to be 226.8 days, with a standard deviation of 13.3 and a range of 196 to 260 days. Six pairs of twins were born in 120 parturitions; thus the apparent twinning rate is higher than that in man.

Cognitive function in unaffected twins discordant for affective disorder

DEFF Research Database (Denmark)

Christensen, Maj Vinberg; Kyvik, Kirsten Ohm; Kessing, Lars Vedel

2006-01-01

. Cognitive performance of 203 High-Risk and Low-Risk twins was compared. RESULTS: Healthy twins discordant for unipolar disorder showed lower performance on almost all measures of cognitive function: selective and sustained attention, executive function, language processing and working and declarative memory...... impairment found seemed to be related to genetic liability, as the MZ High-Risk twins showed significant impairment on selective and sustained attention, executive function, language processing and working and declarative memory, whereas the DZ High-Risk twins presented with significantly lower scores only......, and also after adjustment for demographic variables, subclinical symptoms and minor psychopathology. Healthy twins discordant for bipolar disorder showed lower performance on tests measuring episodic and working memory, also after adjustment for the above-mentioned covariables. The discrete cognitive...

The Child and Adolescent Twin Study in Sweden (CATSS).

Science.gov (United States)

Anckarsäter, Henrik; Lundström, Sebastian; Kollberg, Linnea; Kerekes, Nora; Palm, Camilla; Carlström, Eva; Långström, Niklas; Magnusson, Patrik K E; Halldner, Linda; Bölte, Sven; Gillberg, Christopher; Gumpert, Clara; Råstam, Maria; Lichtenstein, Paul

2011-12-01

The Child and Adolescent Twin Study in Sweden (CATSS) is an ongoing longitudinal twin study targeting all twins born in Sweden since July 1, 1992. Since 2004, parents of twins are interviewed regarding the children's somatic and mental health and social environment in connection with their 9th or 12th birthdays (CATSS-9/12). By January 2010, 8,610 parental interviews concerning 17,220 twins had been completed, with an overall response rate of 80%. At age 15 (CATSS-15) and 18 (CATSS-18), twins and parents complete questionnaires that, in addition to assessments of somatic and mental health, include measures of personality development and psychosocial adaptation. Twin pairs in CATSS-9/12 with one or both twins screening positive for autism spectrum disorders, attention deficit/hyperactivity disorder, tic disorders, developmental coordination disorder, learning disorders, oppositional defiant disorder, conduct disorder, obsessive-compulsive disorder, and/or eating problems have been followed with in-depth questionnaires on family, social environment and personality, and subsequently by clinical assessments at age 15 together with randomly selected population controls, including 195 clinically assessed twin pairs from the first 2 year cohorts (CATSS-15/DOGSS). This article describes the cohorts and study groups, data collection, and measures used. Prevalences, distributions, heritability estimates, ages at onset, and sex differences of mental health problems in the CATSS-9/12, that were analyzed and found to be overall comparable to those of other clinical and epidemiological studies. The CATSS study has the potential of answering important questions on the etiology of childhood mental health problems and their role in the development of later adjustment problems.

Genetic contribution to the relationship between social role function and depressive symptoms in Japanese elderly twins: a twin study.

Science.gov (United States)

Nishihara, Reiko; Inui, Fujio; Kato, Kenji; Tomizawa, Rie; Hayakawa, Kazuo

2011-03-01

Social role function is the capacity to maintain interpersonal relationships and is essential for being independent in the community. Limitations in social role function often coexist with depressive symptoms, suggesting a possible common mechanistic basis. We investigated whether the observed association between these traits is mainly a result of genetic or environmental influences. In 2008, a questionnaire was sent to 745 male twins aged 65 years and older. Our sample included 397 male twins. The number of monozygotic twins was 302, and dizygotic was 95. Among the twin pairs for whom data were available for both twins, 75 twin pairs (150 individuals) were monozygotic and 28 pairs (56 individuals) were dizygotic. Social role function was assessed using the Tokyo Metropolitan Institute of Gerontology Index of Competence. Depressive symptoms were measured by the 15-item version of the Geriatric Depression Scale. Relative importance of genes and environments for the phenotypes was calculated using structural equation analyses. Our results show that genetic influence was the major contributor to the relationship between social role function and depressive symptoms, and non-shared environmental influence was important for overall variation in each trait. We concluded that focusing on a non-shared environment is an essential approach for maintaining social role function and psychological well-being. It is suggested that treatments specific to depressive symptoms are more effective than indirect intervention targeting social role function. © 2011 The Authors. Psychogeriatrics © 2011 Japanese Psychogeriatric Society.

Fetal behavior in normal dichorionic twin pregnancy

NARCIS (Netherlands)

Mulder, E. J. H.; Derks, J. B.; de Laat, M. W. M.; Visser, G. H. A.

2012-01-01

Objectives: A prospective study was performed to compare fetal behavioral development in healthy dichorionic twins and singletons, and identify twin intra-pair associations (synchrony) of fetal movements and rest-activity cycles using different criteria to define synchrony. Subjects and methods:

Quark confinement and the short-range component of general affine gauge gravity

International Nuclear Information System (INIS)

Sijacki, D.

1982-01-01

Within the framework of a gauge field theory based on the general affine space-time symmetry, we propose a certain purely quadratic gauge field lagrangian. In the large-scale region it yields an Einstein-Cartan-like gravity with Newton's constand generated spontaneously, while in the particle domain it yields a renormalizable theory with a confining potential applying to quarks and not to leptons. (orig.)

Application of white beam synchrotron radiation topography to the analysis of twins

International Nuclear Information System (INIS)

Yao, G.D.; Dudley, M.; Hou, S.Y.; DiSalvo, R.

1991-01-01

White beam synchrotron X-ray topography (WBSXRT) has been used to characterize room temperature twinning structures in lanthanum gallate and p-terphenyl single crystals. Both Laue and Bragg geometries are utilized to reveal the nature of twinning in LaGaO 3 . The geometric relationships between the twin related domains and the directions of the corresponding diffracted beams are used to establish the presence of reflection twins on (1anti 12) orth , (1anti 1anti 2) orth and (1anti 10) orth planes. Also described is the application of WBSXRT to reveal the twin law in the solution grown organic crystal p-terphenyl. The active twin plane was unambiguously determined to be (201) by determination of the orientation relationship between parent and twinned structures through Laue pattern analysis. Twin lamellae with the same twin plane were also observed. For both materials, no radiation damage was observed throughout the experiments. These results demonstrate the usefulness of WBSXRT for the study of twins. (orig.)

Application of white beam synchrotron radiation topography to the analysis of twins

Science.gov (United States)

Yao, G.-D.; Dudley, M.; Hou, S.-Y.; DiSalvo, R.

1991-05-01

White beam synchrotron X-ray topography (WBSXRT) has been used to characterize room temperature twinning structures in lanthanum gallate and P-terphenyl single crystals. Both Laue and Bragg geometries are utilized to reveal the nature of twinning in LaGaO 3. The geometric relationships between the twin related domains and the directions of the corresponding diffracted beams are used to establish the presence of reflection twins on (11¯2) orth, (11¯2¯) orth and (11¯0) orth planes. Also described is the application of WBSXRT to reveal the twin law in the solution grown organic crystal p-terphenyl. The active twin plane was unambiguously determined to be (201) by determination of the orientation relationship between parent and twinned structures through Laue pattern analysis. Twin lamellae with the same twin plane were also observed. For both materials, no radiation damage was observed throughout the experiments. These results demonstrate the usefulness of WBSXRT for the study of twins.

Application of white beam synchrotron radiation topography to the analysis of twins

Energy Technology Data Exchange (ETDEWEB)

Yao, G.D.; Dudley, M.; Hou, S.Y.; DiSalvo, R. (Dept. of Materials Science and Engineering, SUNY, Stony Brook, NY (USA))

1991-05-01

White beam synchrotron X-ray topography (WBSXRT) has been used to characterize room temperature twinning structures in lanthanum gallate and p-terphenyl single crystals. Both Laue and Bragg geometries are utilized to reveal the nature of twinning in LaGaO{sub 3}. The geometric relationships between the twin related domains and the directions of the corresponding diffracted beams are used to establish the presence of reflection twins on (1anti 12){sub orth}, (1anti 1anti 2){sub orth} and (1anti 10){sub orth} planes. Also described is the application of WBSXRT to reveal the twin law in the solution grown organic crystal p-terphenyl. The active twin plane was unambiguously determined to be (201) by determination of the orientation relationship between parent and twinned structures through Laue pattern analysis. Twin lamellae with the same twin plane were also observed. For both materials, no radiation damage was observed throughout the experiments. These results demonstrate the usefulness of WBSXRT for the study of twins. (orig.).

Intra-uterine exposure to dual fetal programming sequences among surviving co-twins.

Science.gov (United States)

Salihu, Hamisu M; Ibrahimou, Boubakari; Dagne, Getachew A

2011-01-01

The dynamics of fetal programming following in utero demise of a co-twin are poorly understood. The authors examined fetal programming using a unique application of the change-point analysis method, and identified two types of fetal programming that occurred when a viable twin sibling died in utero, while the co-twin survived. In one type, the initial twin fetal programming trajectory was maintained while in a subset of surviving co-twins a "switch" from a twin to a singleton fetal program (dual fetal programming exposure) was observed. The results suggest that the timing in utero of conversion from a twin to a singleton programming pattern occurred slightly earlier among opposite-sex than in same-sex surviving co-twins. For the conversion from a twin to a singleton program to happen, the surviving co-twin must have attained a "critical mass" when the twin sibling died. Whereas, for same-sex surviving co-twins the critical mass for conversion was the 80th percentile of gestational-age specific birth weight, opposite-sex surviving co-twins converted at a lower critical mass (70th percentile). These novel findings warrant further study to confirm the new hithertofore unknown phenomenon of dual fetal programming sequence, and to determine the implications in terms of subsequent morbidity or mortality during infancy, childhood and adult life.

Ni-Mn-Ga single crystals with very low twinning stress

International Nuclear Information System (INIS)

Straka, L; Haenninen, H; Soroka, A; Sozinov, A

2011-01-01

Twinning stress or mechanical hysteresis associated with the twin boundary motion is one of the most essential parameters which determine the actuating performance of magnetic shape memory alloys. Recent effort at AdaptaMat Ltd. to decrease the twinning stress resulted in a consistent production of Ni-Mn-Ga magnetic shape memory single crystals with the twinning stress of about 0.1 MPa, which is much lower than previously reported. In this work, the mechanical and magnetomechanical response of the developed crystals is discussed in detail and the importance of adjustment of the twin microstructure for obtaining an optimal actuating behavior is illustrated.

The epidemiology of conjoined twins in Latin America.

Science.gov (United States)

Castilla, E E; Lopez-Camelo, J S; Orioli, I M; Sánchez, O; Paz, J E

1988-01-01

Twenty-three cases of symmetrical conjoined twins were registered by the Latin-American Collaborative Study of Congenital Malformations (ECLAMC) in 1,714,952 births, which were observed during the 1967-1986 period in 95 maternity hospitals distributed in eleven Latin-American countries. This results in a birth prevalence rate of about 1/75,000 births. The secular and geographic distribution of this material do not depart from random in spite of one hospital with three cases, and two hospitals with two cases each, within a short time period. These 23 cases include one diprosopus, 3 dicephalus, one ischiopagus, 5 pygopagus, none dipygus, 3 syncephalus, none craniopagus, 9 thoracopagus, one omphalopagus, and one rachipagus. Sex distribution is even, with 12 male and 11 female cases.

Micromechanics of twinning in a TWIP steel

International Nuclear Information System (INIS)

Rahman, K.M.; Jones, N.G.; Dye, D.

2015-01-01

The deformation behaviour of a TWinning Induced Plasticity (TWIP) steel was studied at quasi-static strain rates using synchrotron X-ray diffraction. A {111} RD and {200} RD texture developed from the earliest stages of deformation, which could be reproduced using an elasto-plastic self consistent (EPSC) model. Evidence is found from multiple sources to suggest that twinning was occurring before macroscopic yielding. This included small deviations in the lattice strains, {111} intensity changes and peak width broadening all occurring below the macroscopic yield point. The accumulation of permanent deformation on sub-yield mechanical cycling of the material was found, which further supports the diffraction data. TEM revealed that fine deformation twins similar to those observed in heavily deformed samples formed during sub-yield cycling. It is concluded that twinning had occurred before macroscopic plastic deformation began, unlike the behaviour traditionally expected from hexagonal metals such as Mg

Micromechanics of twinning in a TWIP steel

Energy Technology Data Exchange (ETDEWEB)

Rahman, K.M., E-mail: khandaker.rahman05@imperial.ac.uk [Department of Materials, Royal School of Mines, Imperial College London, Prince Consort Road, London SW7 2BP (United Kingdom); Jones, N.G. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Dye, D. [Department of Materials, Royal School of Mines, Imperial College London, Prince Consort Road, London SW7 2BP (United Kingdom)

2015-05-21

The deformation behaviour of a TWinning Induced Plasticity (TWIP) steel was studied at quasi-static strain rates using synchrotron X-ray diffraction. A {111} RD and {200} RD texture developed from the earliest stages of deformation, which could be reproduced using an elasto-plastic self consistent (EPSC) model. Evidence is found from multiple sources to suggest that twinning was occurring before macroscopic yielding. This included small deviations in the lattice strains, {111} intensity changes and peak width broadening all occurring below the macroscopic yield point. The accumulation of permanent deformation on sub-yield mechanical cycling of the material was found, which further supports the diffraction data. TEM revealed that fine deformation twins similar to those observed in heavily deformed samples formed during sub-yield cycling. It is concluded that twinning had occurred before macroscopic plastic deformation began, unlike the behaviour traditionally expected from hexagonal metals such as Mg.

Short latency compound action potentials from mammalian gravity receptor organs

Science.gov (United States)

Jones, T. A.; Jones, S. M.

1999-01-01

Gravity receptor function was characterized in four mammalian species using far-field vestibular evoked potentials (VsEPs). VsEPs are compound action potentials of the vestibular nerve and central relays that are elicited by linear acceleration ramps applied to the cranium. Rats, mice, guinea pigs, and gerbils were studied. In all species, response onset occurred within 1.5 ms of the stimulus onset. Responses persisted during intense (116 dBSPL) wide-band (50 to 50 inverted question mark omitted inverted question mark000 Hz) forward masking, whereas auditory responses to intense clicks (112 dBpeSPL) were eliminated under the same conditions. VsEPs remained after cochlear extirpation but were eliminated following bilateral labyrinthectomy. Responses included a series of positive and negative peaks that occurred within 8 ms of stimulus onset (range of means at +6 dBre: 1.0 g/ms: P1=908 to 1062 micros, N1=1342 to 1475 micros, P2=1632 to 1952 micros, N2=2038 to 2387 micros). Mean response amplitudes at +6 dBre: 1.0 g/ms ranged from 0.14 to 0.99 microV. VsEP input/output functions revealed latency slopes that varied across peaks and species ranging from -19 to -51 micros/dB. Amplitude-intensity slopes also varied ranging from 0.04 to 0.08 microV/dB for rats and mice. Latency values were comparable to those of birds although amplitudes were substantially smaller in mammals. VsEP threshold values were considerably higher in mammals compared to birds and ranged from -8.1 to -10.5 dBre 1.0 g/ms across species. These results support the hypothesis that mammalian gravity receptors are less sensitive to dynamic stimuli than are those of birds.

Traits of ADHD and autism in girls with a twin brother

DEFF Research Database (Denmark)

Attermann, Jørn; Obel, Carsten; Bilenberg, Niels

2012-01-01

It has been hypothesized that prenatal exposure to testosterone may be associated with traits of attention-deficit/hyperactivity disorder (ADHD) or autism spectrum disorder (ASD). We conducted a population-based study of dizygotic female twins to elucidate this hypothesis, assuming that the sex...... of the co-twin influences the level of prenatal exposure to testosterone. We invited parents of 24,552 3- to 15-year-old twins to answer questionnaires on traits of ADHD and ASD. We analysed the data using a proportional odds model with sex of the co-twin as an instrumental variable for prenatal exposure...... to testosterone of female twins. We received responses for 6,339 girls from dizygotic twin pairs. Odds ratios for male versus female co-twin were 0.71 (95 % confidence interval 0.61-0.81) for ADHD traits and 0.74 (0.66-0.83) for ASD traits, indicating that a twin brother reduces traits of ADHD and ASD in females...

Planck-scale gravity test at PETRA. Letter of intent

Energy Technology Data Exchange (ETDEWEB)

Gharibyan, V.; Balewski, K.

2016-02-15

Quantum or torsion gravity models predict unusual properties of space- time at very short distances. In particular, near the Planck length, around 10{sup -35} m, empty space may behave as a crystal, singly or doubly refractive. This hypothesis, however, remains uncheckable for any direct measurement since the smallest distance accessible in experiment is about 10{sup -19} m at the LHC. Here we propose a laboratory test to measure space birefringence or refractivity induced by gravity. A sensitivity 10{sup -31} m for doubly and 10{sup -28} m for singly refractive vacuum could be reached with PETRA 6 GeV beam exploring UV laser Compton scattering.

Planck-scale gravity test at PETRA. Letter of intent

International Nuclear Information System (INIS)

Gharibyan, V.; Balewski, K.

2016-02-01

Quantum or torsion gravity models predict unusual properties of space- time at very short distances. In particular, near the Planck length, around 10 -35 m, empty space may behave as a crystal, singly or doubly refractive. This hypothesis, however, remains uncheckable for any direct measurement since the smallest distance accessible in experiment is about 10 -19 m at the LHC. Here we propose a laboratory test to measure space birefringence or refractivity induced by gravity. A sensitivity 10 -31 m for doubly and 10 -28 m for singly refractive vacuum could be reached with PETRA 6 GeV beam exploring UV laser Compton scattering.

A twin-family study of general IQ.

NARCIS (Netherlands)

van Leeuwen, M.; van den Berg, S.M.; Boomsma, D.I.

2008-01-01

In this paper we assess the presence of assortative mating, gene-environment interaction and the heritability of intelligence in childhood using a twin family design with twins, their siblings and parents from 112 families. We evaluate two competing hypotheses about the cause of assortative mating

A twin-family study of general IQ

NARCIS (Netherlands)

Leeuwen, M; van den Berg, Stéphanie Martine; Boomsma, D.I.

2008-01-01

In this paper we assess the presence of assortative mating, gene¿environment interaction and the heritability of intelligence in childhood usinga twin family design with twins, their siblings and parents from 112 families. We evaluate two competing hypotheses about the cause of assortativemating in

Motor Development and Physical Activity: A Longitudinal Discordant Twin-Pair Study.

Science.gov (United States)

Aaltonen, Sari; Latvala, Antti; Rose, Richard J; Pulkkinen, Lea; Kujala, Urho M; Kaprio, Jaakko; Silventoinen, Karri

2015-10-01

Previous longitudinal research suggests that motor proficiency in early life predicts physical activity in adulthood. Familial effects including genetic and environmental factors could explain the association, but no long-term follow-up studies have taken into account potential confounding by genetic and social family background. The present twin study investigated whether childhood motor skill development is associated with leisure-time physical activity levels in adulthood independent of family background. Altogether, 1550 twin pairs from the FinnTwin12 study and 1752 twin pairs from the FinnTwin16 study were included in the analysis. Childhood motor development was assessed by the parents' report of whether one of the co-twins had been ahead of the other in different indicators of motor skill development in childhood. Leisure-time physical activity (MET·h·d) was self-reported by the twins in young adulthood and adulthood. Statistical analyses included conditional and ordinary linear regression models within twin pairs. Using all activity-discordant twin pairs, the within-pair difference in a sum score of motor development in childhood predicted the within-pair difference in the leisure-time physical activity level in young adulthood (P men and women.

Separation surgery for total vertical craniopagus twins.

Science.gov (United States)

Goh, Keith Y C

2004-08-01

A pair of conjoined twins aged 11 months underwent investigations, followed by surgical separation in Singapore General Hospital in April 2001. They were joined at the skull vertex and facing in opposite directions. Radiological investigations including cerebral angiography, magnetic resonance imaging and computerized tomographic scans were performed, leading to the diagnosis of total vertical craniopagus. There were two separate brains, with separate arterial circulations, but with a common superior sagittal sinus. Tissue expanders were inserted in the subgaleal space for 6 months of scalp expansion prior to surgery. Pre-operative planning involved the use of virtual reality equipment and life-sized polymer models of the conjoined skulls and brains. Surgical separation of the twins was achieved after approximately 100 h of operating time, using intraoperative image guidance, microsurgical techniques and intraoperative neurophysiologic monitoring. Reconstruction of the dura, calvarium and scalp was performed with artificial dura, absorbable plates and split skin grafts. Postoperative complications included focal cortical infarction, meningitis, and hydrocephalus. Despite these complications, the twins recovered satisfactorily and were discharged to their home country within 6 months. The 3-month outcome was minor disability in one twin and severe developmental delays in the other. Separation surgery is possible for complex cranially-conjoined twins but requires detailed planning and extensive surgical management.

Quantum spreading of a self-gravitating wave-packet in singularity free gravity

Energy Technology Data Exchange (ETDEWEB)

Buoninfante, Luca [Universita di Salerno, Dipartimento di Fisica ' ' E.R. Caianiello' ' , Fisciano (Italy); INFN-Sezione di Napoli, Gruppo Collegato di Salerno, Fisciano (Italy); University of Groningen, Van Swinderen Institute, Groningen (Netherlands); Lambiase, Gaetano [Universita di Salerno, Dipartimento di Fisica ' ' E.R. Caianiello' ' , Fisciano (Italy); INFN-Sezione di Napoli, Gruppo Collegato di Salerno, Fisciano (Italy); Mazumdar, Anupam [University of Groningen, Van Swinderen Institute, Groningen (Netherlands); University of Groningen, Kapteyn Astronomical Institute, Groningen (Netherlands)

2018-01-15

In this paper we will study for the first time how the wave-packet of a self-gravitating meso-scopic system spreads in theories beyond Einstein's general relativity. In particular, we will consider a ghost-free infinite derivative gravity, which resolves the 1/r singularity in the potential - such that the gradient of the potential vanishes within the scale of non-locality. We will show that a quantum wave-packet spreads faster for a ghost-free and singularity-free gravity as compared to the Newtonian case, therefore providing us a unique scenario for testing classical and quantum properties of short-distance gravity in a laboratory in the near future. (orig.)

The Heritability of Dry Eye Disease in a Female Twin Cohort

NARCIS (Netherlands)

Vehof, Jelle; Wang, Bin; Kozareva, Diana; Hysi, Pirro G.; Snieder, Harold; Hammond, Christopher J.

PURPOSE. We estimated the relative importance of genes and environment in dry eye disease (DED) using a classic twin study. METHODS. A large sample of 3930 female monozygotic and dizygotic twins from the UK Adult Twin Registry (TwinsUK) was questioned about the presence of a DED diagnosis and about

Has the "Equal Environments" assumption been tested in twin studies?

Science.gov (United States)

Eaves, Lindon; Foley, Debra; Silberg, Judy

2003-12-01

A recurring criticism of the twin method for quantifying genetic and environmental components of human differences is the necessity of the so-called "equal environments assumption" (EEA) (i.e., that monozygotic and dizygotic twins experience equally correlated environments). It has been proposed to test the EEA by stratifying twin correlations by indices of the amount of shared environment. However, relevant environments may also be influenced by genetic differences. We present a model for the role of genetic factors in niche selection by twins that may account for variation in indices of the shared twin environment (e.g., contact between members of twin pairs). Simulations reveal that stratification of twin correlations by amount of contact can yield spurious evidence of large shared environmental effects in some strata and even give false indications of genotype x environment interaction. The stratification approach to testing the equal environments assumption may be misleading and the results of such tests may actually be consistent with a simpler theory of the role of genetic factors in niche selection.

Quality of life in unaffected twins discordant for affective disorder

DEFF Research Database (Denmark)

Vinberg, Maj; Bech, Per; Kyvik, Kirsten Ohm

2007-01-01

-Risk twins) and without (the control group/Low-Risk twins) a co-twin history of affective disorder were identified through nationwide registers. The aim of the present study was to investigate the hypothesis that a genetic liability to affective disorder is associated with a lower perception of quality......BACKGROUND: The disability and hardship associated with affective disorder is shared by the family members of affective patients and might affect the family member's quality of life. METHOD: In a cross-sectional, high-risk, case-control study, monozygotic (MZ) and dizygotic (DZ) twins with (High...... of life. RESULTS: Univariate analyses showed that quality of life in all domains was impaired for the 121 High-Risk twins compared to the 84 Low-Risk twins. In multiple regression analyses, the differences remained significant after adjustment for sex, age, marital status and years of education. Adjusted...

Kicking Back Cognitive Ageing: Leg Power Predicts Cognitive Ageing after Ten Years in Older Female Twins.

Science.gov (United States)

Steves, Claire J; Mehta, Mitul M; Jackson, Stephen H D; Spector, Tim D

2016-01-01

Many observational studies have shown a protective effect of physical activity on cognitive ageing, but interventional studies have been less convincing. This may be due to short time scales of interventions, suboptimal interventional regimes or lack of lasting effect. Confounding through common genetic and developmental causes is also possible. We aimed to test whether muscle fitness (measured by leg power) could predict cognitive change in a healthy older population over a 10-year time interval, how this performed alongside other predictors of cognitive ageing, and whether this effect was confounded by factors shared by twins. In addition, we investigated whether differences in leg power were predictive of differences in brain structure and function after 12 years of follow-up in identical twin pairs. A total of 324 healthy female twins (average age at baseline 55, range 43-73) performed the Cambridge Neuropsychological Test Automated Battery (CANTAB) at two time points 10 years apart. Linear regression modelling was used to assess the relationships between baseline leg power, physical activity and subsequent cognitive change, adjusting comprehensively for baseline covariates (including heart disease, diabetes, blood pressure, fasting blood glucose, lipids, diet, body habitus, smoking and alcohol habits, reading IQ, socioeconomic status and birthweight). A discordant twin approach was used to adjust for factors shared by twins. A subset of monozygotic pairs then underwent magnetic resonance imaging. The relationship between muscle fitness and brain structure and function was assessed using linear regression modelling and paired t tests. A striking protective relationship was found between muscle fitness (leg power) and both 10-year cognitive change [fully adjusted model standardised β-coefficient (Stdβ) = 0.174, p = 0.002] and subsequent total grey matter (Stdβ = 0.362, p = 0.005). These effects were robust in discordant twin analyses, where within

On axionic field ranges, loopholes and the weak gravity conjecture

International Nuclear Information System (INIS)

Brown, Jon; Cottrell, William; Shiu, Gary; Soler, Pablo

2016-01-01

In this short note we clarify some aspects of the impact that the Weak Gravity Conjecture has on models of (generalized) natural inflation. We address in particular certain technical and conceptual concerns recently raised regarding the stringent constraints and conclusions found in our previous work http://dx.doi.org/10.1007/JHEP10(2015)023. We also point out the difficulties faced by attempts to evade these constraints. These new considerations improve the understanding of the quantum gravity constraints we found and further support the conclusion that it remains challenging for axions to drive natural inflation.

A prospective study of twinning and perinatal mortality in urban Guinea-Bissau

Directory of Open Access Journals (Sweden)

Bjerregaard-Andersen Morten

2012-12-01

Full Text Available Abstract Background Despite twinning being common in Africa, few prospective twin studies have been conducted. We studied twinning rate, perinatal mortality and the clinical characteristics of newborn twins in urban Guinea-Bissau. Methods The study was conducted at the Bandim Health Project (BHP, a health and demographic surveillance site in Bissau, the capital of Guinea-Bissau. The cohort included all newborn twins delivered at the National Hospital Simão Mendes and in the BHP study area during the period September 2009 to August 2011 as well as singleton controls from the BHP study area. Data regarding obstetric history and pregnancy were collected at the hospital. Live children were examined clinically. For a subset of twin pairs zygosity was established by using genetic markers. Results Out of the 5262 births from mothers included in the BHP study area, 94 were twin births, i.e. a community twinning rate of 18/1000. The monozygotic rate was 3.4/1000. Perinatal mortality among twins vs. singletons was 218/1000 vs. 80/1000 (RR = 2.71, 95% CI: 1.93-3.80. Among the 13783 hospital births 388 were twin births (28/1000. The hospital perinatal twin mortality was 237/1000. Birth weight  Conclusions Twins had a very high perinatal mortality, three-fold higher than singletons. A birth weight 

Vestibular stimulation interferes with the dynamics of an internal representation of gravity.

Science.gov (United States)

De Sá Teixeira, Nuno Alexandre; Hecht, Heiko; Diaz Artiles, Ana; Seyedmadani, Kimia; Sherwood, David P; Young, Laurence R

2017-11-01

The remembered vanishing location of a moving target has been found to be displaced downward in the direction of gravity (representational gravity) and more so with increasing retention intervals, suggesting that the visual spatial updating recruits an internal model of gravity. Despite being consistently linked with gravity, few inquiries have been made about the role of vestibular information in these trends. Previous experiments with static tilting of observers' bodies suggest that under conflicting cues between the idiotropic vector and vestibular signals, the dynamic drift in memory is reduced to a constant displacement along the body's main axis. The present experiment aims to replicate and extend these outcomes while keeping the observers' bodies unchanged in relation to physical gravity by varying the gravito-inertial acceleration using a short-radius centrifuge. Observers were shown, while accelerated to varying degrees, targets moving along several directions and were required to indicate the perceived vanishing location after a variable interval. Increases of the gravito-inertial force (up to 1.4G), orthogonal to the idiotropic vector, did not affect the direction of representational gravity, but significantly disrupted its time course. The role and functioning of an internal model of gravity for spatial perception and orientation are discussed in light of the results.

Two sets of twins with selective mutism: neuropsychological findings.

Science.gov (United States)

Gray, Robert M; Jordan, Catherine M; Ziegler, Richard S; Livingston, Ronald B

2002-03-01

Neuropsychological data are reviewed from two sets of dizygotic twins presenting with selective mutism characterized by situation specific anxiety, extreme passive behavior, lack of responsivity, lack of peer interaction, and a chronic course of selective mutism. Both sets of twins had a history of prematurity and delayed speech development. One set of twins presented with normal intelligence and normal receptive language skills but with expressive language and oral motor sequencing difficulties. The second set of twins presented with Verbal IQ deficits and significant receptive and expressive language deficits. A summary of current conceptualizations regarding etiology and treatment of selective mutism is provided.

Increased risk of type 2 diabetes in elderly twins

DEFF Research Database (Denmark)

Poulsen, Pernille; Grunnet, Louise G; Pilgaard, Kasper

2009-01-01

OBJECTIVE: Genetic susceptibility, low birth weight (LBW), and aging are key etiological factors in the development of type 2 diabetes. LBW is common among twins. It is unknown whether twin status per se is associated with risk of type 2 diabetes, and valid concordance rates of type 2 diabetes...... in twins on a lifetime perspective are lacking. RESEARCH DESIGN AND METHODS: A clinical study was done on a population-based cohort of same-sex elderly monozygotic (MZ) and dizygotic (DZ) twins (n = 297) and singleton control subjects (C) (n = 71) including measures of anthropometry and glucose tolerance...

Concordance Rates of Adolescent Idiopathic Scoliosis in a Danish Twin Population

DEFF Research Database (Denmark)

Simony, Ane; Carreon, Leah Y; Højmark, Karen

2016-01-01

STUDY DESIGN: Clinical, radiological and genetic determination of zygosity of twin pairs from the Danish Twin Registry who self-reported having Adolescent Idiopathic Scoliosis (AIS). OBJECTIVE: To establish concordance rates of AIS. SUMMARY OF BACKGROUND DATA: The aetiology of and the true mode...... reported. METHODS: All 46,418 twins registered in the Danish Twin Registry born from 1931 to 1982 were sent a survey, which included questions about scoliosis. The survey was returned by 34,944 individuals (75.3%) representing 23,204 pairs. From this study, 548 individuals representing 274 complete twin...... pairs where at least one twin self-reported having scoliosis were invited to a clinical and radiological examination. Zygosity was established by genetic testing. RESULTS: 182 individuals (33.2%) of the original cohort agreed to participate, 128 of whom had scoliosis by self-report. There were 91 twin...

Artificial gravity: head movements during short-radius centrifugation

NARCIS (Netherlands)

Young, L. R.; Hecht, H.; Lyne, L. E.; Sienko, K. H.; Cheung, C. C.; Kavelaars, J.

2001-01-01

Short-radius centrifugation is a potential countermeasure to long-term weightlessness. Unfortunately, head movements in a rotating environment induce serious discomfort, non-compensatory vestibulo-ocular reflexes, and subjective illusions of body tilt. In two experiments we investigated the effects

A lateral cephalometric study of craniofacial variation in Korean child twins

Energy Technology Data Exchange (ETDEWEB)

Lee, Sang Rae; You, Dong Soo [College of Dentistry, Seoul National University, Seoul (Korea, Republic of)

1974-11-15

A study was performed to investigate the degree of similarities and differences in components of craniofacial complex between Korean twins and normal children by lateral cephalometric analysis. Dimensions of S-N, S-Ba, N-Ba, Go-Me, Ar-Go and Ar-Me were plotted against linear measurement and angles of N-S-Ba and gonial against angular measurement in twins and control groups. The lateral cephalograms of twin were composed of 88 twins aged from 7 to 12:44 males aged 10.65 and 44 females aged 9. 55, while those of 50 normalities were composed of 25 male and 25 female aged 10.9 respectively. In order to analyze growth proportion and sexual differences, twins were divided into 3 groups according to two year age intervals and the author compared male with female in 3 groups. For the purpose of observing similarities and differences in twins and normalities by sex, total twins were compared with normalities. The obtained results were as follows: 1. There was no difference in craniofacial complex between twins and normalities. 2. In general, the measurements of male were larger than those of female in both twins and normalities, but there were no statistical significances of sexual differences in both groups. 3. The growth proportion of mandible by aging was larger than that of face in twins. 4. The growth pattern of gonial angle showed slight reducing tendency in twin by aging. 5. There was little difference in the growth proportion of both male and female.

A lateral cephalometric study of craniofacial variation in Korean child twins

International Nuclear Information System (INIS)

Lee, Sang Rae; You, Dong Soo

1974-01-01

A study was performed to investigate the degree of similarities and differences in components of craniofacial complex between Korean twins and normal children by lateral cephalometric analysis. Dimensions of S-N, S-Ba, N-Ba, Go-Me, Ar-Go and Ar-Me were plotted against linear measurement and angles of N-S-Ba and gonial against angular measurement in twins and control groups. The lateral cephalograms of twin were composed of 88 twins aged from 7 to 12:44 males aged 10.65 and 44 females aged 9. 55, while those of 50 normalities were composed of 25 male and 25 female aged 10.9 respectively. In order to analyze growth proportion and sexual differences, twins were divided into 3 groups according to two year age intervals and the author compared male with female in 3 groups. For the purpose of observing similarities and differences in twins and normalities by sex, total twins were compared with normalities. The obtained results were as follows: 1. There was no difference in craniofacial complex between twins and normalities. 2. In general, the measurements of male were larger than those of female in both twins and normalities, but there were no statistical significances of sexual differences in both groups. 3. The growth proportion of mandible by aging was larger than that of face in twins. 4. The growth pattern of gonial angle showed slight reducing tendency in twin by aging. 5. There was little difference in the growth proportion of both male and female.

Preparing for Twins

Science.gov (United States)

... Ribbon Commands Skip to main content Turn off Animations Turn on Animations Our Sponsors Log in | Register Menu Log in | ... challenges with twins. He also can suggest helpful reading material or refer you to organizations that help ...

Atopic diseases in twins born after assisted reproduction.

Science.gov (United States)

Jäderberg, Ida; Thomsen, Simon F; Kyvik, Kirsten O; Skytthe, Axel; Backer, Vibeke

2012-03-01

We examined the risk of atopic diseases in twins born after assisted reproduction. Data on atopic diseases and assisted reproduction in 9694 twin pairs, 3-20 years of age, from the Danish Twin Registry were collected via multidisciplinary questionnaires. The risk of atopic diseases in twins born after assisted reproduction was compared with the risk in twins born after spontaneous conception using logistic regression and variance components analysis. Children born after assisted reproduction did not have a different risk of atopic outcomes (adjusted odds ratios [95% confidence intervals] for asthma: 0.95 [0.85, 1.07], P = 0.403; hay fever: 1.01 [0.86, 1.18], P = 0.918; and atopic dermatitis: 1.02 [0.81, 1.11], P = 0.773 respectively) compared with children born after spontaneous conception. Assisted reproduction did not modify the heritability of atopic diseases. This study does not support an association between assisted reproduction and development of atopic diseases. This result must be confirmed in subsequent studies, preferably of singleton populations. © 2011 Blackwell Publishing Ltd.

Twinning of cubic diamond explains reported nanodiamond polymorphs

Science.gov (United States)

Németh, Péter; Garvie, Laurence A. J.; Buseck, Peter R.

2015-12-01

The unusual physical properties and formation conditions attributed to h-, i-, m-, and n-nanodiamond polymorphs has resulted in their receiving much attention in the materials and planetary science literature. Their identification is based on diffraction features that are absent in ordinary cubic (c-) diamond (space group: Fd-3m). We show, using ultra-high-resolution transmission electron microscope (HRTEM) images of natural and synthetic nanodiamonds, that the diffraction features attributed to the reported polymorphs are consistent with c-diamond containing abundant defects. Combinations of {113} reflection and rotation twins produce HRTEM images and d-spacings that match those attributed to h-, i-, and m-diamond. The diagnostic features of n-diamond in TEM images can arise from thickness effects of c-diamonds. Our data and interpretations strongly suggest that the reported nanodiamond polymorphs are in fact twinned c-diamond. We also report a new type of twin ( rotational), which can give rise to grains with dodecagonal symmetry. Our results show that twins are widespread in diamond nanocrystals. A high density of twins could strongly influence their applications.

Arizona Twin Project: a focus on early resilience.

Science.gov (United States)

Lemery-Chalfant, Kathryn; Clifford, Sierra; McDonald, Kristy; O'Brien, T Caitlin; Valiente, Carlos

2013-02-01

The Arizona Twin Project is an ongoing longitudinal study designed to elucidate the genetic and environmental influences underlying the development of early competence and resilience to common mental and physical health problems during infancy and childhood. Participants are a sample of 600 twins (25% Hispanic) recruited from birth records in the state of Arizona, United States. Primary caregivers were interviewed on twins' development and early social environments when twins were 12 and 30 months of age. Measures include indices of prenatal and obstetrical risk coded from hospital medical records, as well as primary caregiver-report questionnaires assessing multiple indicators of environmental risk and resilience (e.g., parental warmth and control, family and social support), twins' developmental maturity, temperament, health, behavior problems, and competencies. Preliminary findings highlight the importance of the early environment for infant and toddler health and well-being, both directly and as a moderator of genetic influences. Future directions include a third longitudinal assessment in middle childhood examining daily bidirectional relations between sleep, health behaviors, stress, and mood.

Twinning of cubic diamond explains reported nanodiamond polymorphs.

Science.gov (United States)

Németh, Péter; Garvie, Laurence A J; Buseck, Peter R

2015-12-16

The unusual physical properties and formation conditions attributed to h-, i-, m-, and n-nanodiamond polymorphs has resulted in their receiving much attention in the materials and planetary science literature. Their identification is based on diffraction features that are absent in ordinary cubic (c-) diamond (space group: Fd-3m). We show, using ultra-high-resolution transmission electron microscope (HRTEM) images of natural and synthetic nanodiamonds, that the diffraction features attributed to the reported polymorphs are consistent with c-diamond containing abundant defects. Combinations of {113} reflection and rotation twins produce HRTEM images and d-spacings that match those attributed to h-, i-, and m-diamond. The diagnostic features of n-diamond in TEM images can arise from thickness effects of c-diamonds. Our data and interpretations strongly suggest that the reported nanodiamond polymorphs are in fact twinned c-diamond. We also report a new type of twin ( rotational), which can give rise to grains with dodecagonal symmetry. Our results show that twins are widespread in diamond nanocrystals. A high density of twins could strongly influence their applications.

Salivary cortisol in unaffected twins discordant for affective disorder

DEFF Research Database (Denmark)

Vinberg, Maj; Bennike, Bente; Kyvik, Kirsten Ohm

2008-01-01

. In conclusion, a high genetic liability to affective disorder was associated with a higher evening cortisol level, but not with awakening cortisol level. Future prospective family, high-risk and twin studies are needed to decide whether abnormalities in the HPA axis can be identified as an endophenotype......Dysfunction in the hypothalamic-pituitary-adrenal (HPA) axis has been proposed as a biological endophenotype for affective disorders. In the present study the hypothesis that a high genetic liability to affective disorder is associated with higher cortisol levels was tested in a cross......-sectional high-risk study. Healthy monozygotic (MZ) and dizygotic (DZ) twins with (High-Risk twins) and without (Low-Risk twins) a co-twin history of affective disorder were identified through nationwide registers. Awakening and evening salivary cortisol levels were compared between the 190 High- and Low...

Massive Gravity

OpenAIRE

de Rham, Claudia

2014-01-01

We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali–Gabadadze–Porrati model (DGP), cascading gravity, and ghost-free massive gravity. We then explore their theoretical and phenomenological consistency, proving the absence of Boulware–Deser ghosts and reviewing the Vainshtein mechanism and the cosmological solutions in these models. Finally, we present alt...

Higher Prevalence of Left-Handedness in Twins? Not After Controlling Birth Time Confounders.

Science.gov (United States)

Heikkilä, Kauko; Vuoksimaa, Eero; Saari-Kemppainen, Aulikki; Kaprio, Jaakko; Rose, Richard J; Haukka, Jari; Pitkäniemi, Janne; Iivanainen, Matti

2015-10-01

Pregnancy- and birth-related factors may have an effect on handedness. Compared with singletons, twins have a lower birth weight, shorter gestational age, and are at higher risk for birth complications. We tested whether the prevalence of left-handedness is higher among twins than singletons, and if so, whether that difference is fully explained by pregnancy and birth-related differences between twins and singletons. We analyzed Finnish population-based datasets; included were 8,786 twins and 5,892 singletons with information on birth weight (n = 12,381), Apgar scores (n = 11,129), and gestational age (n = 11,811). Two twin cohorts were involved: FinnTwin12 included twins born during 1983-1987, and FinnTwin16 included twins born during 1974-1979. We had two comparison groups of singletons: 4,101 individuals born during 1986-1988 and enrolled in the Helsinki Ultrasound Trial, and 1,791 individuals who were partners of FinnTwin16 twins. We used logistic regression models with writing hand as the outcome for comparison and evaluating effects of covariates. Left-handedness was more common in twins (9.67%) than in singletons (8.27%; p = .004). However, Apgar scores were associated with handedness, and after controlling for covariates, we found no difference in the prevalence of left-handedness between twins and singletons. Increased left-handedness among twins, often reported by others, was evident in our data, but only among our older twin cohorts, and that association disappeared after removing effects of perinatal covariates.

The fracture behavior of twinned Cu nanowires: A molecular dynamics simulation

Energy Technology Data Exchange (ETDEWEB)

Sun, Jiapeng, E-mail: sun.jiap@gmail.com [College of Mechanics and Materials, Hohai University, Nanjing 210098 (China); Fang, Liang [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi Province (China); Ma, Aibin, E-mail: aibin-ma@hhu.edu.cn [College of Mechanics and Materials, Hohai University, Nanjing 210098 (China); Jiang, Jinghua [College of Mechanics and Materials, Hohai University, Nanjing 210098 (China); Han, Ying [Key Laboratory of Advanced Structural Materials, Ministry of Education, Changchun University of Technology, Changchun 130012, Jilin Province (China); Chen, Huawei [Department of Applied Physics, School of Science, Xi’an Jiaotong University, Xi’an 710049, Shaanxi Province (China); Han, Jing [School of Mechanical and Electrical Engineering, China University of Mining and Technology, Xuzhou 221116, Jiangsu Province (China)

2015-05-14

The molecular dynamics simulations are performed to explore the fracture behavior and the ductility of the twinned Cu nanowires containing orthogonally oriented growth CTBs due to the uniaxial tensile deformation. The results reveal that, the fracture behavior and the ductility of the twinned nanowires are not related to the length of the nanowires but also intensively related to the twin boundary spacing. When the twin boundary space is changed, the twinned nanowires undergo three distinct failure modes which include ductile fracture, brittle fracture and ductile-to-brittle transition depending on the length of the nanowires. We also find a reduction in the ductility of the twinned nanowires, which is ascribed to the deformation localization induced by the Lomer dislocation and the rapid necking resulted from the twinning partial slipping. Finally, the atomic-level process that occurs during deformation until final fracture are examined in detail, and a new formation mechanism of the Lomer dislocation is observed when a 90° partial dislocation transmits across a coherent twin boundary.

The fracture behavior of twinned Cu nanowires: A molecular dynamics simulation

International Nuclear Information System (INIS)

Sun, Jiapeng; Fang, Liang; Ma, Aibin; Jiang, Jinghua; Han, Ying; Chen, Huawei; Han, Jing

2015-01-01

The molecular dynamics simulations are performed to explore the fracture behavior and the ductility of the twinned Cu nanowires containing orthogonally oriented growth CTBs due to the uniaxial tensile deformation. The results reveal that, the fracture behavior and the ductility of the twinned nanowires are not related to the length of the nanowires but also intensively related to the twin boundary spacing. When the twin boundary space is changed, the twinned nanowires undergo three distinct failure modes which include ductile fracture, brittle fracture and ductile-to-brittle transition depending on the length of the nanowires. We also find a reduction in the ductility of the twinned nanowires, which is ascribed to the deformation localization induced by the Lomer dislocation and the rapid necking resulted from the twinning partial slipping. Finally, the atomic-level process that occurs during deformation until final fracture are examined in detail, and a new formation mechanism of the Lomer dislocation is observed when a 90° partial dislocation transmits across a coherent twin boundary

Risk factors for testicular cancer: a case-control study in twins.

Science.gov (United States)

Swerdlow, A J; De Stavola, B L; Swanwick, M A; Mangtani, P; Maconochie, N E

1999-06-01

Early life and anthropometric risk factors for testicular cancer were examined in a case-control study in England and Wales in which affected male twins were compared with their unaffected male co-twins. Questionnaire data was obtained for 60 twin pairs. Significantly raised risk of testicular cancer occurred in twins who had longer arms and legs than their co-twin. There was a significant excess of testicular cancer reported in non-twin brothers, as well as in twin brothers, of cases. Risk was also significantly raised in relation to cryptorchidism. The results on limb length suggest that factors, perhaps nutritional, affecting growth before puberty, may be causes of testicular cancer. The results on risk in brothers add to evidence of a large genetic component in aetiology of the tumour. The risk associated with cryptorchidism in the twins accords with the hypothesis that cryptorchidism is causally associated with testicular cancer because it is a cause of the malignancy, rather than because the same maternal factors experienced in utero cause both conditions.

Recent results on short-range gravity experiment

International Nuclear Information System (INIS)

Hata, Maki; Akiyama, Takashi; Ikeda, Yuki; Kawamura, Hirokazu; Narita, Keigo; Ninomiya, Kazufumi; Ogawa, Naruya; Sato, Toshiaki; Seitaibashi, Etsuko; Sekiguchi, Yuta; Tsutsui, Ryosuke; Yazawa, Kazumasa; Murata, Jiro

2009-01-01

According to the ADD model, deviation from Newton's inverse square law is expected at below sub-millimeter scale. Present study is an experimental investigation of the Newton's gravitational law at a short range scale. We have developed an experimental setup using torsion balance bar, and succeeded to confirm the inverse square law at a centimeter scale. In addition, composition dependence of gravitational constant G is also tested at the centimeter scale, motivated to test the weak equivalence principle.

Scales of gravity

International Nuclear Information System (INIS)

Dvali, Gia; Kolanovic, Marko; Nitti, Francesco; Gabadadze, Gregory

2002-01-01

We propose a framework in which the quantum gravity scale can be as low as 10 -3 eV. The key assumption is that the standard model ultraviolet cutoff is much higher than the quantum gravity scale. This ensures that we observe conventional weak gravity. We construct an explicit brane-world model in which the brane-localized standard model is coupled to strong 5D gravity of infinite-volume flat extra space. Because of the high ultraviolet scale, the standard model fields generate a large graviton kinetic term on the brane. This kinetic term 'shields' the standard model from the strong bulk gravity. As a result, an observer on the brane sees weak 4D gravity up to astronomically large distances beyond which gravity becomes five dimensional. Modeling quantum gravity above its scale by the closed string spectrum we show that the shielding phenomenon protects the standard model from an apparent phenomenological catastrophe due to the exponentially large number of light string states. The collider experiments, astrophysics, cosmology and gravity measurements independently point to the same lower bound on the quantum gravity scale, 10 -3 eV. For this value the model has experimental signatures both for colliders and for submillimeter gravity measurements. Black holes reveal certain interesting properties in this framework

Improved twin detection via tracking of individual Kikuchi band intensity of EBSD patterns.

Science.gov (United States)

Rampton, Travis M; Wright, Stuart I; Miles, Michael P; Homer, Eric R; Wagoner, Robert H; Fullwood, David T

2018-02-01

Twin detection via EBSD can be particularly challenging due to the fine scale of certain twin types - for example, compression and double twins in Mg. Even when a grid of sufficient resolution is chosen to ensure scan points within the twins, the interaction volume of the electron beam often encapsulates a region that contains both the parent grain and the twin, confusing the twin identification process. The degradation of the EBSD pattern results in a lower image quality metric, which has long been used to imply potential twins. However, not all bands within the pattern are degraded equally. This paper exploits the fact that parent and twin lattices share common planes that lead to the quality of the associated bands not degrading; i.e. common planes that exist in both grains lead to bands of consistent intensity for scan points adjacent to twin boundaries. Hence, twin boundaries in a microstructure can be recognized, even when they are associated with thin twins. Proof of concept was performed on known twins in Inconel 600, Tantalum, and Magnesium AZ31. This method was then used to search for undetected twins in a Mg AZ31 structure, revealing nearly double the number of twins compared with those initially detected by standard procedures. Copyright © 2017 Elsevier B.V. All rights reserved.

Deformation twinning in zinc-aluminium single crystals after slip

International Nuclear Information System (INIS)

Lukac, P.; Kral, F.; Trojanova, Z.; Kral, R.

1993-01-01

Deformation twinning in Zn-Al single crystals deformed by slip in the basal system is examined. The influence of temperature and the content of aluminium in zinc on the twinning stress is investigated in the temperature range from 198 to 373 K. It is shown that the twinning stress rises with increasing temperature and increases with the concentration of Al atoms. (orig.)

Trends in the obstetric features and management of twin pregnancies.

LENUS (Irish Health Repository)

Smith, K E

2010-03-01

There are no reports outlining the trends in obstetric features and clinical management of twin pregnancies in an Irish obstetric population. The aim of this study was to investigate these factors for all twin pregnancies delivered during the 19 year period between 1989 and 2007, at Galway University Hospital (GUH). There were 52,199 infants delivered at GUH, of which 1594 infants (3.05% of births) were twins, related to 797 twin pregnancies. The overall incidence of twin pregnancies was 1.52%, increasing from 0.8%-1.0% in the early years of the study to 1.7-1.8% in the latter years of the study (P<0.001). There was a significant increase in incidence of twins born to mothers aged 30-39 years, alongside a significant reduction to mothers aged 20-29 years (P<0.01). The caesarean section rate overall was 41.5% (331\\/797), of which 54% (n=179) were elective, and 46% (n=152) were emergency, representing an emergency caesarean section rate of 19.1% of all twin pregnancies, and of 24.6% after exclusion of elective caesarean sections. The caesarean section rate for twins increased from 30% in 1989 to greater than 50% in the latter years of the study (P<0.01), related largely to a significant increase in elective caesarean sections (P<0.01). The combined vaginal-caesarean delivery rate was remarkably low at 0.75% of all twin pregnancies, and 1% after exclusion of elective caesarean sections. The preterm delivery rates were 4.1% (<32 weeks), and 16.3% (<36 weeks), with an overall perinatal mortality rate of 37 per 1000. These findings highlight the altered demographic and clinical aspects of twin pregnancies in an Irish obstetric population.

Proliferation of twinning in hexagonal close-packed metals: Application to magnesium

Science.gov (United States)

Sun, D.; Ponga, M.; Bhattacharya, K.; Ortiz, M.

2018-03-01

Plastic deformation of metallic alloys usually takes place through slip, but occasionally involves twinning. In particular, twinning is important in hexagonal close packed (HCP) materials where the easy slip systems are insufficient to accommodate arbitrary deformations. While deformation by slip mechanisms is reasonably well understood, comparatively less is known about deformation by twinning. Indeed, the identification of relevant twinning modes remains an art. In this paper, we develop a framework combining a fundamental kinematic definition of twins with large-scale atomistic calculations to predict twinning modes of crystalline materials. We apply this framework to magnesium where there are two accepted twin modes, tension and compression, but a number of anomalous observations. Remarkably, our framework shows that there is a very large number of twinning modes that are important in magnesium. Thus, in contrast to the traditional view that plastic deformation is kinematically partitioned between a few modes, our results suggest that deformation in HCP materials is the result of an energetic and kinetic competition between numerous possibilities. Consequently, our findings suggest that the commonly used models of deformation need to be extended in order to take into account a broader and richer variety of twin modes, which, in turn, opens up new avenues for improving the mechanical properties.

Long-Term Neuropsychological Outcome in Preterm Twins

Directory of Open Access Journals (Sweden)

Giovanni Iannone

2006-01-01

Full Text Available Few long-term studies have yet described neuropsychological outcome in preterm twins. Our aim was to assess, by long-term evaluation, neuropsychological outcome in preterm twins in order to define a correct follow-up program. Our study was a cohort one, with an index and a comparison group. Neonatal medical records of all preterm newborns admitted to our centre between 1991 and 1997 were reviewed and selected patients were recalled. The sample population included two matched groups of children aged 6—12 years, 86 twins and 86 singletons, submitted to paediatric, neurological, psychological, and ophthalmological examinations. Inclusion criteria were twin pregnancy and gestational age 27—36 weeks for index group; same gestational age, but single pregnancy, for the comparison group. All children underwent paediatric and neuropsychiatric examinations, cognitive assessment, and psychological evaluation by standardized tests for screening of learning specific disorders and language difficulties, and finally, ophthalmological examination. In order to study their role in predicting neuropsychological outcome, we examined some perinatal prognostic factors by statistical analysis. Unfavourable neuropsychological outcome was observed in 55/172 (32% children, with different prevalence in the two groups, 42/172 (24% in twins and 13/172 (8% in singletons. Statistical analysis performed for examined prognostic factors showed significant differences in neuropsychological outcome with regard only to gestational age < 32 weeks, low birth weight, intraventricular haemorrhage, and periventricular leukomalacia. The incidence of neuropsychological diseases in the two groups showed significant difference about language and learning difficulties. Our data suggest that preterm twins represent a particular high-risk category of premature babies, mostly regarding the risk of so-called “minimal brain dysfunction”, so a careful follow-up is recommended.

Between Two Worlds: Twin Peaks and the Film/Television Divide

Directory of Open Access Journals (Sweden)

Siobhan Lyons

2017-04-01

Full Text Available In 1992, the year David Lynch’s cult television series 'Twin Peaks' was pulled off air, Lynch released the film 'Twin Peaks: Fire Walk with Me', a prequel to the television series which filled in some of the gaps left from the series finale cliff-hanger. The film was received with unanimously negative reviews from critics and fans alike, condemning both its subtle and obvious deviations from the series and its inclusion of the character Laura Palmer, whose absence was a crucial narrative device at the centre of 'Twin Peaks'. In film form, the 'Twin Peaks' narrative suffers from thematic inconsistencies and aesthetic deviations. The scope of 'Twin Peaks' seems much more capable in the setting of television and its gradual, episodic set-up. In recent years, however, with the announcement of a revival of the series, retrospective analysis of 'Fire Walk with Me' has become more positive, and the film has also become an integral part of the overall 'Twin Peaks' canon. Nevertheless, the transition from television to film in the case of 'Twin Peaks' has remained a point of fan and scholarly controversy, with issues of continuity, narrative and aesthetics between the two different mediums continually being addressed and compared. In light of the news that the new season of 'Twin Peaks' is set to be released in 2017, this article examines the significance of 'Fire Walk with Me' as a cinematic counterpart and prequel to the original series, and how this has helped shape – whether positively or not – the overall narrative of 'Twin Peaks'.

Significance of Dauphiné twins in crystallographic fabrics of quartz tectonites

Science.gov (United States)

Eske Sørensen, Bjørn

2014-05-01

Dauphine twins are commonly found in quartz tectonites, however their role in deformation processes are not completely understood. This study represents a new attempt to understand the interaction between slip systems and Dauphine twins in deforming quartz-rich rocks at different temperatures. There is no doubt that Dauphine twins are mobilized under stress as this has been shown by experiments for single crystals and in polycrystalline aggregates where distinct crystallographic fabrics develop in previously randomly oriented aggregates related to minimization of elastic energy (Tullis 1972). However in quartz tectonites the Dauphine twin process is a part of interplay between plastic deformation and recovery processes which depends on PT, strain-rate and fluid composition and availability. In quartz tectonites with Y-girdle C-axis (GBM-regime) fabrics Dauphiné twins are abundant, relating different parts of r- and z rhomb "comet" distributions. This is interpreted as completion between prism slip and Dauphiné twinning. Slip rotates grains such that CRSS is low on the prism planes, but then Dauphiné twin boundaries sweeps through the grain back to the orientation giving lower stored elastic energy. The faster recovery at higher temperatures gives subgrain walls slowing down twin movement across the mm-sized grain of the GBM regime. At lower temperatures in the SGR-regime grain-size is reduced and different rotations of the grains are happening due to the domination of rhomb and basal slip. Because recrystallization is effective relative to grain-size the grains are commonly free of internal strain and subgrain walls, allowing the favorably oriented Dauphiné twin member to sweep across the whole grain overwhelming the unfavorably oriented Dauphiné twin member. As a consequence high strain reduces the number of Dauphiné twins and quartz rhomb fabrics appear trigonal, missing the "comet" shape of the GBM regime rhomb fabrics. Since Dauphiné twinning is also

[About twins: Epidemiological, genetic, and obstetrical aspects, specific risks, and outcome].

Science.gov (United States)

Tauzin, M; Felix, A; Michot, C; Dedieu, C; Aoust, L; Fortas, F; Guillier, C; Ngo, J; Wachter, P-Y; Petermann, L; Kermorvant-Duchemin, E

2017-12-01

The incidence of twin pregnancies has increased steadily for the last 40 years due to assisted reproductive technology and increased maternal childbearing age. Multiple pregnancies, especially monochorionic twin pregnancies, carry a high risk for the mother and the fetuses and require close follow-up. Twins are exposed to a higher risk of perinatal anoxia, in utero fetal demise, preterm birth, congenital malformations, fetal growth restriction, and vascular complications. Compared to singletons, twins are at higher risk of perinatal mortality and impaired neurodevelopmental outcome, justifying a thorough follow-up by pediatricians, including assessment and management of familial and psychosocial impact. This paper discusses the epidemiological, obstetrical, and genetic issues raised by twin pregnancies and reviews the data on the perinatal and neurological long-term outcomes of twins, as well as the psychosocial impact of multiple births on twins and their families. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

PPN-limit of Fourth Order Gravity inspired by Scalar-Tensor Gravity

OpenAIRE

Capozziello, S.; Troisi, A.

2005-01-01

Based on the {\\it dynamical} equivalence between higher order gravity and scalar-tensor gravity the PPN-limit of fourth order gravity is discussed. We exploit this analogy developing a fourth order gravity version of the Eddington PPN-parameters. As a result, Solar System experiments can be reconciled with higher order gravity, if physical constraints descending from experiments are fulfilled.

Identification of promising Twin Hub networks : Report of Work Package 1 of the Intermodal rail freight Twin hub Network Northwest Europe - project (final report)

NARCIS (Netherlands)

Kreutzberger, E.D.; Konings, J.W.; Meijer, S.; Witteveen, C.; Meijers, B.M.; Pekin, E.; Macharis, C.; Kiel, J.; Kawabata, Y.; Vos, W.

2014-01-01

This report is the first deliverable of the project Intermodal Rail Freight Twin Hub Network Northwest Europe. We call its subject Twin hub network and the organisational entity to carry out the actions the Twin hub project. The project is funded by INTERREG NWE (programme IVb). Its work started in

Quantitative XRD analysis of {110} twin density in biotic aragonites.

Science.gov (United States)

Suzuki, Michio; Kim, Hyejin; Mukai, Hiroki; Nagasawa, Hiromichi; Kogure, Toshihiro

2012-12-01

{110} Twin densities in biotic aragonite have been estimated quantitatively from the peak widths of specific reflections in powder X-ray diffraction (XRD) patterns, as well as direct confirmation of the twins using transmission electron microscopy (TEM). Influence of the twin density on the peak widths in the XRD pattern was simulated using DIFFaX program, regarding (110) twin as interstratification of two types of aragonite unit layers with mirrored relationship. The simulation suggested that the twin density can be estimated from the difference of the peak widths between 111 and 021, or between 221 and 211 reflections. Biotic aragonite in the crossed-lamellar microstructure (three species) and nacreous microstructure (four species) of molluscan shells, fish otoliths (two species), and a coral were investigated. The XRD analyses indicated that aragonite crystals in the crossed-lamellar microstructure of the three species contain high density of the twins, which is consistent with the TEM examination. On the other hand, aragonite in the nacre of the four species showed almost no difference of the peak widths between the paired reflections, indicating low twin densities. The results for the fish otoliths were varied between the species. Such variation of the twin density in biotic aragonites may reflect different schemes of crystal growth in biomineralization. Copyright © 2012 Elsevier Inc. All rights reserved.

Monozygotic twins with CAPN5 autosomal dominant neovascular inflammatory vitreoretinopathy.

Science.gov (United States)

Rowell, Hannah A; Bassuk, Alexander G; Mahajan, Vinit B

2012-01-01

The purpose of this study was to describe the clinical findings in a set of monozygotic twins with autosomal dominant neovascular inflammatory vitreoretinopathy (ADNIV) over a 23-year period. A pair of female twins were examined between 26 and 49 years of age. The concordance and discordance of their clinical features were determined. The CAPN5 gene was sequenced using genomic DNA. Both twins of an affected father demonstrated Stage I ADNIV with mild vitreous cells and a negative b-wave on electroretinography. Genetic analysis confirmed a guanine to thymine nucleotide (c.728G>T, pArg243Leu) mutation in the CAPN5 gene. Over the course of 23 years, each twin progressed to stage III disease, showing posterior uveitis, cystoid macular edema, intraocular fibrosis, early retinal neovascularization, retinal degeneration, and cataract. Disease progression varied moderately between each twin and was asymmetrical between eyes. Twin A had 20/70 and 20/125 in the right and left eye, respectively, and underwent vitrectomy surgery and intravitreal injections with bevacizumab for recurrent cystoid macular edema. Twin B maintained 20/20 and 20/40 in the right and left eye, respectively without intervention. There was asymmetry between the eyes and some discordance in the rate of disease progression in these monozygotic twins with ADNIV. The overall high disease concordance suggests genetic factors play a major role in clinical manifestations in CAPN5 vitreoretinopathy.

Terrestrial gravity data analysis for interim gravity model improvement

Science.gov (United States)

1987-01-01

This is the first status report for the Interim Gravity Model research effort that was started on June 30, 1986. The basic theme of this study is to develop appropriate models and adjustment procedures for estimating potential coefficients from terrestrial gravity data. The plan is to use the latest gravity data sets to produce coefficient estimates as well as to provide normal equations to NASA for use in the TOPEX/POSEIDON gravity field modeling program.

Prenatal x-ray exposure and childhood cancer in twins

International Nuclear Information System (INIS)

Harvey, E.B.; Boice, J.D. Jr.; Honeyman, M.; Flannery, J.T.

1985-01-01

A case-control study was conducted to investigate the relation between prenatal exposure to x-rays and childhood cancer, including leukemia, in over 32,000 twins born in Connecticut from 1930 to 1969. Twins as opposed to single births were chosen for study to reduce the likelihood of medical selection bias, since twins were often exposed to x-rays to diagnose the twin pregnancy or to determine fetal positioning before delivery and not because of medical conditions that may conceivably pre-dispose to cancer. Each of 31 incident cases of cancer, identified by linking the Connecticut twin and tumor registries, was matched with four twin controls according to sex, year of birth, and race. Records of hospitals, radiologists, and private physicians were searched for histories of x-ray exposure and other potentially important risk factors. Documented prenatal x-ray exposures were found for 39 per cent of the cases (12 of 31) and for 26 per cent of the controls (28 of 109). No other pregnancy, delivery, or maternal conditions were associated with cancer risk except low birth weight: 38 per cent of the cases as compared with 25 per cent of the controls weighed under 2.27 kg at birth. When birth weight was adjusted for, twins in whom leukemia or other childhood cancer developed were twice as likely to have been exposed to x-rays in utero as twins who were free of disease (relative risk, 2.4; 95 per cent confidence interval, 1.0 to 5.9). The results, though based on small numbers, provide further evidence that low-dose prenatal irradiation may increase the risk of childhood cancer

There are two twin shadows, but einstein is one

Directory of Open Access Journals (Sweden)

Popović Marko E.

2012-01-01

Full Text Available 2011 is the international year of chemistry, and it is exactly 100 years past after the P. Langevin promotion of “twin paradox” problem. The hundred year old problem still demands its solution. Twin paradox, established by a physicist, has been representing a nightmare for philosophers, physicists, chemists, and biologists until these days. After a hundred years, it is time to try to close this page in long history of misunderstanding of the special relativity. This analysis has three main assumptions. First, biological systems are a part of physical world and therefore they behave in accordance to the physical laws according to Schrödinger. Second, according to Von Bertalanffy the biological systems are open thermodynamic systems. Because of that the approach of non-equilibrium thermodynamics was used for analyzing the twin paradox. Third, rise of entropy is according to Hyflick strongly connected with aging. Entropy can be taken as a measure of cell age or even human age according to Silva et al. and Gladyshev. So entropy invariance strongly suggests that both twins should be the same age, so there is a potential problem for twin paradox with the second law. The only possible influence of relativity on the chemical reaction rate is time dilatation. However time flow does not cause the aging process, so time dilatation cannot have any influence on it. So, after detailed analysis, it is concluded that there is no twin paradox in reality. Both twins will be exactly in same thermodynamic state and bio-logical age. The traveler twin will notice time dilatation, but this relativistic effect has no influence on the aging process.

Sleep-EEG in dizygotic twins discordant for Williams syndrome.

Science.gov (United States)

Bódizs, Róbert; Gombos, Ferenc; Szocs, Katalin; Réthelyi, János M; Gerván, Patrícia; Kovács, Ilona

2014-01-30

Reports on twin pairs concordant and discordant for Williams syndrome were published before, but no study unravelled sleep physiology in these cases yet. We aim to fill this gap by analyzing sleep records of a twin pair discordant for Williams syndrome extending our focus on presleep wakefulness and sleep spindling. We performed multiplex ligation-dependent probe amplification of the 7q11.23 region of a 17 years old dizygotic opposite-sex twin pair discordant for Williams syndrome. Polysomnography of laboratory sleep at this age was analyzed and followed-up after 1.5 years by ambulatory polysomnography. Sleep stages scoring, EEG power spectra and sleep spindle analyses were carried out. The twin brother showed reduced levels of amplification for all of the probes in the 7q11.23 region indicating a typical deletion spanning at least 1.038 Mb between FKBP6 and CLIP2. The results of the twin sister showed normal copy numbers in the investigated region. Lower sleep times and efficiencies, as well as higher slow wave sleep percents of the twin brother were evident during both recordings. Roughly equal NREM, Stage 2 and REM sleep percents were found. EEG analyses revealed state and derivation-independent decreases in alpha power, lack of an alpha spectral peak in presleep wakefulness, as well as higher NREM sleep sigma peak frequency in the twin brother. Faster sleep spindles with lower amplitude and shorter duration characterized the records of the twin brother. Spectra show a striking reliability and correspondence between the two situations (laboratory vs. home records). Alterations in sleep and specific neural oscillations including the alpha/sigma waves are inherent aspects of Williams syndrome.

Association of Depressive Symptoms and Heart Rate Variability in Vietnam War-Era Twins: A Longitudinal Twin Difference Study.

Science.gov (United States)

Huang, Minxuan; Shah, Amit; Su, Shaoyong; Goldberg, Jack; Lampert, Rachel J; Levantsevych, Oleksiy M; Shallenberger, Lucy; Pimple, Pratik; Bremner, J Douglas; Vaccarino, Viola

2018-05-16

Depressive symptoms are associated with lower heart rate variability (HRV), an index of autonomic dysregulation, but the direction of the association remains unclear. To investigate the temporal association between depression and HRV. A longitudinal, cross-lagged twin difference study, with baseline assessments from March 2002 to March 2006 (visit 1) and a 7-year follow-up (visit 2) at an academic research center with participants recruited from a national twin registry. Twins (n = 166) from the Vietnam Era Twin Registry, who served in the US military during the Vietnam War, and were discordant for depression at baseline were recruited. At both visits, depressive symptoms were measured using the Beck Depression Inventory-II (BDI-II), and HRV was measured through 24-hour electrocardiogram monitoring. To assess the direction of the association, within-pair differences in multivariable mixed-effects regression models were examined, and standardized β coefficients for both pathways were calculated. The associations were evaluated separately in monozygotic and dizygotic twins. In the final analytic sample (N = 146), all participants were men, 138 (95%) were white, and the mean (SD) age was 54 (3) years at baseline. Results showed consistent associations between visit 1 HRV and visit 2 BDI score across all HRV domains and models (β coefficients ranging from -0.14 to -0.29), which were not explained by antidepressants or other participant characteristics. The magnitude of the association was similar in the opposite pathway linking visit 1 BDI score to visit 2 HRV, with β coefficients ranging from 0.05 to -0.30, but it was largely explained by antidepressant use. In stratified analysis by zygosity, significant associations were observed in monozygotic and dizygotic twins for the path linking visit 1 HRV to visit 2 BDI score, although the associations were slightly stronger in dizygotic twins. The association between depression and autonomic dysregulation

Twin's Birth-Order Differences in Height and Body Mass Index From Birth to Old Age: A Pooled Study of 26 Twin Cohorts Participating in the CODATwins Project.

Science.gov (United States)

Yokoyama, Yoshie; Jelenkovic, Aline; Sund, Reijo; Sung, Joohon; Hopper, John L; Ooki, Syuichi; Heikkilä, Kauko; Aaltonen, Sari; Tarnoki, Adam D; Tarnoki, David L; Willemsen, Gonneke; Bartels, Meike; van Beijsterveldt, Toos C E M; Saudino, Kimberly J; Cutler, Tessa L; Nelson, Tracy L; Whitfield, Keith E; Wardle, Jane; Llewellyn, Clare H; Fisher, Abigail; He, Mingguang; Ding, Xiaohu; Bjerregaard-Andersen, Morten; Beck-Nielsen, Henning; Sodemann, Morten; Song, Yun-Mi; Yang, Sarah; Lee, Kayoung; Jeong, Hoe-Uk; Knafo-Noam, Ariel; Mankuta, David; Abramson, Lior; Burt, S Alexandra; Klump, Kelly L; Ordoñana, Juan R; Sánchez-Romera, Juan F; Colodro-Conde, Lucia; Harris, Jennifer R; Brandt, Ingunn; Nilsen, Thomas Sevenius; Craig, Jeffrey M; Saffery, Richard; Ji, Fuling; Ning, Feng; Pang, Zengchang; Dubois, Lise; Boivin, Michel; Brendgen, Mara; Dionne, Ginette; Vitaro, Frank; Martin, Nicholas G; Medland, Sarah E; Montgomery, Grant W; Magnusson, Patrik K E; Pedersen, Nancy L; Aslan, Anna K Dahl; Tynelius, Per; Haworth, Claire M A; Plomin, Robert; Rebato, Esther; Rose, Richard J; Goldberg, Jack H; Rasmussen, Finn; Hur, Yoon-Mi; Sørensen, Thorkild I A; Boomsma, Dorret I; Kaprio, Jaakko; Silventoinen, Karri

2016-04-01

We analyzed birth order differences in means and variances of height and body mass index (BMI) in monozygotic (MZ) and dizygotic (DZ) twins from infancy to old age. The data were derived from the international CODATwins database. The total number of height and BMI measures from 0.5 to 79.5 years of age was 397,466. As expected, first-born twins had greater birth weight than second-born twins. With respect to height, first-born twins were slightly taller than second-born twins in childhood. After adjusting the results for birth weight, the birth order differences decreased and were no longer statistically significant. First-born twins had greater BMI than the second-born twins over childhood and adolescence. After adjusting the results for birth weight, birth order was still associated with BMI until 12 years of age. No interaction effect between birth order and zygosity was found. Only limited evidence was found that birth order influenced variances of height or BMI. The results were similar among boys and girls and also in MZ and DZ twins. Overall, the differences in height and BMI between first- and second-born twins were modest even in early childhood, while adjustment for birth weight reduced the birth order differences but did not remove them for BMI.

Strong gravity effects of rotating black holes: quasi-periodic oscillations

International Nuclear Information System (INIS)

Aliev, Alikram N; Esmer, Göksel Daylan; Talazan, Pamir

2013-01-01

We explore strong gravity effects of the geodesic motion in the spacetime of rotating black holes in general relativity and braneworld gravity. We focus on the description of the motion in terms of three fundamental frequencies: the orbital frequency, the radial and vertical epicyclic frequencies. For a Kerr black hole, we perform a detailed numerical analysis of these frequencies at the innermost stable circular orbits and beyond them as well as at the characteristic stable orbits, at which the radial epicyclic frequency attains its highest value. We find that the values of the epicyclic frequencies for a class of stable orbits exhibit good qualitative agreement with the observed frequencies of the twin peaks quasi-periodic oscillations (QPOs) in some black hole binaries. We also find that at the characteristic stable circular orbits, where the radial (or the vertical) epicyclic frequency has maxima, the vertical and radial epicyclic frequencies exhibit an approximate 2:1 ratio even in the case of near-extreme rotation of the black hole. Next, we perform a similar analysis of the fundamental frequencies for a rotating braneworld black hole and argue that the existence of such a black hole with a negative tidal charge, whose angular momentum exceeds the Kerr bound in general relativity, does not confront with the observations of high-frequency QPOs. (paper)

A high resolution gravity model for Venus - GVM-1

Science.gov (United States)

Nerem, R. S.; Bills, B. G.; Mcnamee, J. B.

1993-01-01

A spherical harmonic model of the gravitational field of Venus complete to degree and order 50 has been developed using the S-band Doppler tracking data of the Pioneer Venus Orbiter (PVO) collected between 1979 and 1982. The short wavelengths of this model could only be resolved near the PVO periapse location (about 14 deg N latitude), therefore a priori constraints were applied to the model to bias poorly observed coefficients towards zero. The resulting model has a half-wavelength resolution of 400 km near the PVO periapse location, but the resolution degrades to greater than 1000 km near the poles. This gravity model correlates well with a degree 50 spherical harmonic expansion of the Venus topography derived from a combination of Magellan and PVO data. New tracking data from Magellan's gravity mission should provide some improvement to this model, although a complete model of the Venusian gravity field will depend on tracking of Magellan after the circularization of its orbit using aerobraking.

Buoyant Helical Twin-Axial Wire Antenna

Science.gov (United States)

2016-11-15

February 2017 The below identified patent application is available for licensing. Requests for information should be addressed to...300169 1 of 9 BUOYANT HELICAL TWIN-AXIAL WIRE ANTENNA CROSS REFERENCE TO OTHER PATENT APPLICATIONS [0001] This application is a divisional...application and claims the benefit of the filing date of United States Patent Application No. 14/280,889; filed on May 19, 2014; and entitled “Twin-Axial

NOTE: Arterio-venous flow between monochorionic twins determined during intra-uterine transfusion

Science.gov (United States)

van Gemert, Martin J. C.; van den Wijngaard, Jeroen P. H. M.; Lopriore, Enrico; Pasman, Suzanne A.; Vandenbussche, Frank P. H. A.

2008-04-01

Twin-twin transfusion syndrome (TTTS) is a severe complication of monozygotic (identical) twin fetuses sharing one single (monochorionic) placenta. TTTS is caused by a net inter-twin transfusion of blood through placental anastomoses, from one twin (the donor) to the other (the recipient), which link the two feto-placental circulations. Currently, the only reliable method to measure the net inter-twin transfusion clinically is when incomplete laser therapy of TTTS occurs and one of the twins becomes anemic and requires an intra-uterine transfusion of adult red blood cells. Then, differences between adult hemoglobin concentrations measured during the transfusion and at birth relate not only to the net inter-twin transfusion but also to the finite lifetime of the adult red blood cells. We have analyzed this situation, derived the differential equations of adult hemoglobin in the donor and recipient twins, given the solutions and given expressions relating the net inter-twin flow with clinically measured parameters. We have included single and multiple intra-uterine transfusions. In conclusion, because incomplete laser therapy occurs frequently, and some cases require an intra-uterine transfusion, this method may allow collecting a wealth of net inter-twin flow data from clinicians involved in laser therapy of TTTS. To aid to the widespread use of this method, we have presented the equations as clearly as possible in tables for easy use by others.

A twin study of body dysmorphic concerns.

Science.gov (United States)

Monzani, B; Rijsdijk, F; Anson, M; Iervolino, A C; Cherkas, L; Spector, T; Mataix-Cols, D

2012-09-01

Dysmorphic concern refers to an excessive preoccupation with a perceived or slight defect in physical appearance. It lies on a continuum of severity from no or minimal concerns to severe concerns over one's appearance. The present study examined the heritability of dysmorphic concerns in a large sample of twins. Twins from the St Thomas UK twin registry completed a valid and reliable self-report measure of dysmorphic concerns, which also includes questions about perceived body odour and malfunction. Twin modelling methods (female twins only, n=3544) were employed to decompose the variance in the liability to dysmorphic concerns into additive genetic, shared and non-shared environmental factors. Model-fitting analyses showed that genetic factors accounted for approximately 44% [95% confidence intervals (CI) 36-50%] of the variance in dysmorphic concerns, with non-shared environmental factors and measurement error accounting for the remaining variance (56%; 95% CI 50-63%). Shared environmental factors were negligible. The results remained unchanged when excluding individuals reporting an objective medical condition/injury accounting for their concern in physical appearance. Over-concern with a perceived or slight defect in physical appearance is a heritable trait, with non-shared environmental factors also playing an important role in its causation. The results are relevant for various psychiatric disorders characterized by excessive concerns in body appearance, odour or function, including but not limited to body dysmorphic disorder.

Academic performance of opposite-sex and same-sex twins in adolescence

DEFF Research Database (Denmark)

Juel Ahrenfeldt, Linda; Petersen, Inge; Johnson, Wendy

2015-01-01

confirm a masculinizing effect of a male co-twin regarding for instance perception and cognition it remains unclear whether intra-uterine hormone transfer exists in humans. Our aim was to test the potential influences of testosterone on academic performance in OS twins. We compared ninth-grade test scores...... not provide evidence for a masculinization of female twins with male co-twins with regard to academic performance in adolescence....... and teacher ratings of OS (n=1812) and SS (n=4054) twins as well as of twins and singletons (n=13,900) in mathematics, physics/chemistry, Danish, and English. We found that males had significantly higher test scores in mathematics than females (.06-.15 SD), whereas females performed better in Danish (.33...

Twin edge colorings of certain square graphs and product graphs

Directory of Open Access Journals (Sweden)

R Rajarajachozhan

2016-04-01

Full Text Available A twin edge $k\\!$-coloring of a graph $G$ is a proper edge $k$-coloring of $G$ with the elements of $\\mathbb{Z}_k$ so that the induced vertex $k$-coloring, in which the color of a vertex $v$ in $G$ is the sum in $\\mathbb{Z}_k$ of the colors of the edges incident with $v,$ is a proper vertex $k\\!$-coloring. The minimum $k$ for which $G$ has a twin edge $k\\!$-coloring is called the twin chromatic index of $G.$ Twin chromatic index of the square $P_n^2,$ $n\\ge 4,$ and the square $C_n^2,$ $n\\ge 6,$ are determined. In fact, the twin chromatic index of the square $C_7^2$ is $\\Delta+2,$ where $\\Delta$ is the maximum degree. Twin chromatic index of $C_m\\,\\Box\\,P_n$ is determined, where $\\Box$ denotes the Cartesian product. $C_r$ and $P_r$ are, respectively, the cycle, and the path on $r$ vertices each.

Language Development of Three- to Twelve-Year-Old Twins Compared to Singletons.

Science.gov (United States)

Dʼhaeseleer, Evelien; Geenens, Eline; Parmentier, Sarah; Corthals, Paul; Van Lierde, Kristiane

2016-01-01

The language development of twins tends to lag behind in comparison to that of singletons. The purpose of this study was to compare expressive and receptive language skills of 3- to 12-year-old twins with singletons. Secondly, correlations between language differences between twins and singletons and age were investigated. Twenty-four twins with a mean age of 5.1 years participated in the study. The control group consisted of 24 singletons who were matched for gender and age. Language development was investigated using the Clinical Evaluation of Language Fundamentals. Twins scored significantly lower for expressive and receptive language skills compared to singletons. Even when excluding preterm-born children, twins still scored significantly lower for expressive language skills. There was no correlation between age and language differences between twins and their matched singletons. Twins score lower for expressive and receptive language skills compared to singletons, and preterm birth cannot be regarded as the main cause for the language delay. The language delay in twins is rather mild but does not seem to decrease with increasing age. © 2016 S. Karger AG, Basel.

Embryo-transfer twinning and performance efficiency in beef production.

Science.gov (United States)

Guerra-Martinez, P; Dickerson, G E; Anderson, G B; Green, R D

1990-12-01

Effects of twinning on efficiency of beef production were estimated from results of bilateral transfer of two Angus x Hereford (AxH) embryos into each of 241 heifers and 84 cows (H, A, HxA or Holstein x H) over 4 yr. Calves were weaned at 180 d and fed either 220 d in a feedlot (1977) or 170 d on forage and 140 d in a feedlot (1978 to 1980). Effects of parity, twinning and sex of calf were estimated as covariates within year-breed of dam. Pregnancy at 45 to 60 d of gestation was 68% in heifers (H) and 74% in cows (C), with 40% single (S) and 60% twin (T) births. Dystocia was 28% in H vs 10% in C (P less than .05), and tended to be less (P greater than .05) for T than S in H. More placentas were retained (P less than .05) for T than for S in both H (35 vs 12%) and C (24 vs 4%). Twin gestations averaged 3 d shorter and subsequent calving intervals 13 d longer (P less than .05), but total calf mortality was slightly higher (P greater than .05). Abortions were 4% in H only. Twinning females lost maternal weight during late gestation (P less than .05) when crowding limited voluntary feed intake, while fetal requirements were 60% higher (P less than .01). Twins increased milk output 25% (P less than .05), but 11% higher feed intake maintained cow weight during lactation. Twinning reduced birth weight 13% and weaning weight 17% (P less than .05), but 400-d feedlot weight only 9% because of compensating feedlot gain. Twins gained 18% faster than S during postweaning 170-d forage feeding, but 5% slower in feedlot to 8% lighter 490-d weight (P less than .05). Assuming 40% higher veterinary and labor costs for twins, estimated integrated herd costs per unit of age-constant output value would be lower for T than for S production by about 24% for marketing either at weaning or at 400 d.

Extension twin variant selection during uniaxial compression of a magnesium alloy

DEFF Research Database (Denmark)

Pei, Y.; Godfrey, A.; Jiang, J.

2012-01-01

is also observed in that smaller grains are less likely to contain lower ranked twin variants. For both 5% and 10% compression no clear relationship exists between the volume fraction of each twin variant in a given grain population and the Schmid factor for the twin variant. A positive linear......Samples of the magnesium alloy AZ31 have been deformed by compression to strains of 5% and 10% and microstructural observations made to investigate the activation of specific {1 0 1¯ 2} extension twin variants. The twinning has been analyzed on a grain-by-grain basis for more than 260 grains...... to determine both the number of extension twin variants in each grain, and the volume fraction of each. At 5% strain approx. 30% of the grains contain twins corresponding to variants with the third or lower ranked Schmid factor, with the fraction increasing to 40% after 10% compression. A grain size effect...

The ethics of separating conjoined twins: two arguments against.

Science.gov (United States)

Kallberg, Luke

2018-02-01

I argue that the separation of conjoined twins in infancy or early childhood is unethical (rare exceptions aside). Cases may be divided into three types: both twins suffer from lethal abnormalities, only one twin has a lethal abnormality, or neither twin does. In the first kind of case, there is no reason to separate, since both twins will die regardless of treatment. In the third kind of case, I argue that separation at an early age is unethical because the twins are likely to achieve an irreplaceably good quality of life-the goods of conjoinment-that separation takes away. Evaluation of this possibility requires maturation past early childhood. Regarding the second type, I point out that with conceivable but unrecorded exceptions, these cases will consistently involve sacrifice separation. I present an argument that sacrifice separation is unethical, but in some cases a moral dilemma may exist in which separation and refraining from separation are both unethical. Perhaps in such cases a decision can be made on non-moral grounds; however, the possibility of such a decision serves not to mitigate but to underscore the fact that the separation is unethical. My conclusion, which applies to all three types of cases, is that it is unethical to separate conjoined twins before their developing personalities give some reliable indication as to whether they desire separation and whether they will achieve those goods of conjoinment.

Twinning in muskox and the cytogenetic investigation of a freemartin

Directory of Open Access Journals (Sweden)

N. J. Reindl

1993-12-01

Full Text Available The occurrence of twinning has been documented for muskox in both wild and captive populations. Of two known captive twin births only one set survived beyond 120 days. In both cases the twins were male-female pairs and both females showed abnormal sexual development. Two sets of stillborn twins have also been recorded. All four stillborn fetuses were female and none showed anomalies of the reproductive tract upon post-mortem examination. Blood cultures from the surviving male and female twins revealed that both were chimeric, indicating the admixture of fetal blood. Fibroblast cultures were normal for the respective sex of each individual. The freemartin heifer had anatomical abnormalities of the clitoris as well as the secondary sex characteristics of a male.

INTEGRATED TWIN TOWERS DAN ISLAMISASI ILMU

Directory of Open Access Journals (Sweden)

Syaifuddin Syaifuddin

2013-05-01

Full Text Available This paper shows some idea as follows: First, integrated design of the Twin Towers as the changing action from IAIN to UIN Sunan Ampel. The religion and general knowledge’s position of Twin Towers’ integrated design is not mixed into one, but it works individually, and at the certain time are united in mutual dialogue. Second, Islamize design is done in order to criticize the general knowledge which has western sources and are secular, materialistic, and individualistic. In the process to Islamize the knowledge, Islamic knowledge tries to intervene the general knowledge in order to filter it so the knowledge will be Islamized. Consequently, to Islamize knowledge is to give an Islamic concept into general knowledge. Third, there are the similarities and differences between integrated design knowledge based on Islamic knowledge and integrated Twin Towers. The difference is in its epistemology process. The similarity is in the curriculum (ontology and objective (axiology. In the curriculum, the examined knowledge is religion and general knowledge. While the objective, Islamize knowledge and integrated Twin Towers aims to integrate religion and general knowledge, to dialogue, to communicate, and to synergy, so it can be a knowledge which is intact-integral-integrative.

Gene-Environment Interplay in Twin Models

Science.gov (United States)

Hatemi, Peter K.

2013-01-01

In this article, we respond to Shultziner’s critique that argues that identical twins are more alike not because of genetic similarity, but because they select into more similar environments and respond to stimuli in comparable ways, and that these effects bias twin model estimates to such an extent that they are invalid. The essay further argues that the theory and methods that undergird twin models, as well as the empirical studies which rely upon them, are unaware of these potential biases. We correct this and other misunderstandings in the essay and find that gene-environment (GE) interplay is a well-articulated concept in behavior genetics and political science, operationalized as gene-environment correlation and gene-environment interaction. Both are incorporated into interpretations of the classical twin design (CTD) and estimated in numerous empirical studies through extensions of the CTD. We then conduct simulations to quantify the influence of GE interplay on estimates from the CTD. Due to the criticism’s mischaracterization of the CTD and GE interplay, combined with the absence of any empirical evidence to counter what is presented in the extant literature and this article, we conclude that the critique does not enhance our understanding of the processes that drive political traits, genetic or otherwise. PMID:24808718

Level of anxiety in parents of high-risk premature twins.

Science.gov (United States)

Zanardo, V; Freato, F; Cereda, C

1998-01-01

We attempted to define parental anxiety in a population of parents of high-risk premature twins (mean birth weight 1,493 +/- 227 kg; mean gestational age 33 +/- 3.5 weeks), admitted to III level NICU. We specifically examined the following factors; gestational age of the twins, whether or not the twins had ventilatory support, pulmonary sequelae, major malformations or intra-ventricular hemorrhage, parental gender and highest level of education obtained by the parent. In the immediate pre-discharge period and a month later, a questionnaire (State-Trait Anxiety Inventory) was given to all parents of premature twins presenting for the discharge. The parents of 30 twins entered the study twice, at the discharge of their first twin (mean postnatal age 40 +/- 32 days), and one month later. They included 15 mothers and 11 fathers, aged 33 +/- 5.5 and 33 +/- 4.2 years, and at the second evaluation 11 mothers and 10 fathers, respectively. As case-controls we examined parental anxiety of fifteen consecutive singleton high-risk prematures, with equal gestational age, discharged immediately after. Our results indicate that the parents of high-risk twin and singleton prematures present an elevated, lasting state-trait anxiety level. Pre- and post-discharge parental anxiety is more elevated (not significant) in twinning with respect to the prematurity alone. When assessed separately by parental gender, in both these groups an increased (not significant) anxiety was persistently found in the mothers. We recommend that, although neonatologists generally define the discharge of the high-risk premature based upon the acquired stabilization of vital parameters, they pay special attention to the twin group we have identified which is at increased risk for predischarge parental anxiety.

Superconducting gravity gradiometer for sensitive gravity measurements. I. Theory

International Nuclear Information System (INIS)

Chan, H.A.; Paik, H.J.

1987-01-01

Because of the equivalence principle, a global measurement is necessary to distinguish gravity from acceleration of the reference frame. A gravity gradiometer is therefore an essential instrument needed for precision tests of gravity laws and for applications in gravity survey and inertial navigation. Superconductivity and SQUID (superconducting quantum interference device) technology can be used to obtain a gravity gradiometer with very high sensitivity and stability. A superconducting gravity gradiometer has been developed for a null test of the gravitational inverse-square law and space-borne geodesy. Here we present a complete theoretical model of this instrument. Starting from dynamical equations for the device, we derive transfer functions, a common mode rejection characteristic, and an error model of the superconducting instrument. Since a gradiometer must detect a very weak differential gravity signal in the midst of large platform accelerations and other environmental disturbances, the scale factor and common mode rejection stability of the instrument are extremely important in addition to its immunity to temperature and electromagnetic fluctuations. We show how flux quantization, the Meissner effect, and properties of liquid helium can be utilized to meet these challenges

Dualities and emergent gravity: Gauge/gravity duality

Science.gov (United States)

de Haro, Sebastian

2017-08-01

In this paper I develop a framework for relating dualities and emergence: two notions that are close to each other but also exclude one another. I adopt the conception of duality as 'isomorphism', from the physics literature, cashing it out in terms of three conditions. These three conditions prompt two conceptually different ways in which a duality can be modified to make room for emergence; and I argue that this exhausts the possibilities for combining dualities and emergence (via coarse-graining). I apply this framework to gauge/gravity dualities, considering in detail three examples: AdS/CFT, Verlinde's scheme, and black holes. My main point about gauge/gravity dualities is that the theories involved, qua theories of gravity, must be background-independent. I distinguish two senses of background-independence: (i) minimalistic and (ii) extended. I argue that the former is sufficiently strong to allow for a consistent theory of quantum gravity; and that AdS/CFT is background-independent on this account; while Verlinde's scheme best fits the extended sense of background-independence. I argue that this extended sense should be applied with some caution: on pain of throwing the baby (general relativity) out with the bath-water (extended background-independence). Nevertheless, it is an interesting and potentially fruitful heuristic principle for quantum gravity theory construction. It suggests some directions for possible generalisations of gauge/gravity dualities. The interpretation of dualities is discussed; and the so-called 'internal' vs. 'external' viewpoints are articulated in terms of: (i) epistemic and metaphysical commitments; (ii) parts vs. wholes. I then analyse the emergence of gravity in gauge/gravity dualities in terms of the two available conceptualisations of emergence; and I show how emergence in AdS/CFT and in Verlinde's scenario differ from each other. Finally, I give a novel derivation of the Bekenstein-Hawking black hole entropy formula based on

Variant selection of primary, secondary and tertiary twins in a deformed Mg alloy

International Nuclear Information System (INIS)

Mu, Sijia; Jonas, John J.; Gottstein, Günter

2012-01-01

Samples of magnesium alloy AZ31 were deformed in plane strain compression in a channel die at 100 °C and a strain rate of 5 × 10 −3 s −1 . The initial texture was favorably oriented for extension twinning. At a true strain of ε = −0.11, many primary extension twins were observed to consume their parent grains completely. Furthermore, numerous secondary contraction twins formed within the primary extension twins and some tertiary extension twins grew within the secondary contraction twins. The orientations of the parent grains and all three generations of twins were measured. The twin variants selected during each of the three stages of twinning were determined by electron backscatter diffraction techniques and the absent potential twin variants were also identified. The way in which the selected primary extension twins grow so as to consume the parent grains and contact all the neighboring grains is explained in terms of the accommodation strains imposed on the neighboring grains. The analysis shows that the primary twin selected is not necessarily the variant with the highest Schmid factor but the one that requires the least accommodation work in most of the neighboring grains. The same principle was found to hold for the secondary and tertiary twins. By contrast, potential high Schmid factor twins that required the consumption of appreciable accommodation energy did not form. A Taylor simulation produced similar results and indicates that the accommodation strain concept is consistent with the principle of the minimization of plastic work.

Impact of chorionicity on first-trimester nuchal translucency screening in ART twin pregnancies.

Science.gov (United States)

Flöck, A; Reinsberg, J; Berg, C; Gembruch, U; Geipel, A

2013-08-01

Nuchal translucency (NT) measurement in assisted reproduction treatment (ART) twins is less extensively investigated. Therefore, the present study compared NT measurements of spontaneously conceived twins with ART twins in dichorionic (DC) and monochorionic (MC) pregnancies. Retrospective analysis of 706 unaffected twins between 11 + 0 and 13 + 6 weeks conceived either spontaneously (n = 362) or with ART (n = 344). The group with spontaneous conception included 234 DC (64.6%) and 128 MC (35.4%) pregnancies. In the ART group, 326 were DC (94.7%) and 18 were MC (5.3%). NT values were transformed into multiples of median (MoM). In the DC group, no significant differences between ART and spontaneously conceived twins (NT MoM 1.06 ± 0.28 vs 1.03 ± 0.29; p > 0.05) were observed. NT MoM of MC ART twins was higher compared with spontaneous MC twins (1.23 ± 0.82 vs 0.99 ± 0.27; p = 0.011). Although the incidence of twin-to-twin transfusion syndrome (TTTS) was higher among ART twins (11.1% vs 4.7%), inter-twin NT difference was similar between pregnancies with TTTS (0.42 ± 0.21) or without (0.40 ± 0.71). Measurement of NT thickness in DC ART twins achieves comparable results with twins conceived spontaneously. Conclusions in MC twins are limited; however, higher NT MoM was not related to TTTS or selective intrauterine growth restriction. © 2013 John Wiley & Sons, Ltd.

Gender Differences in Mother-Neonate Twin Interaction.

Science.gov (United States)

Riese, Marilyn L.

To investigate differences in mothers' interaction patterns with their neonate twins based on birth order, relative size at birth, or gender, 37 neonate twins and their mothers were observed during the first 10 minutes of a feeding in a hospital nursery. Time-sampling recordings were made of maternal behaviors related to proximal stimulation,…

Diecephalic thoraco-omphalopagus conjoined twins: case report ...

African Journals Online (AJOL)

We present a case report of conjoined twins discovered at 17 weeks gestation on routine trans-abdominal ultrasound in a 27 year old woman. The twins were joined at the chest and upper abdomen. They shared a heart, liver, sternum and diaphragm. The patient opted for termination of the pregnancy which was performed ...

Dissecting complex phenotypes using the genomics of twins

DEFF Research Database (Denmark)

Tan, Qihua; Ohm Kyvik, Kirsten; Kruse, Torben A

2010-01-01

of human diseases. Besides, twins not only serve as ideal samples for disease gene mapping using conventional genetic markers but also represent an excellent model for associating DNA copy number variations, a structural genetic marker, with human diseases. It is believed that, with the rapid development...... in biotechniques and new advances in bioinformatics, the unique samples of twins will make new contributions to our understanding of the nature and nurture in complex disease development and in human health. This paper aims at summarizing the new uses of twins in current genetic studies and suggesting novel...

Heritability of retinal vascular fractals: a twin study

DEFF Research Database (Denmark)

Vergmann, Anna Stage; Broe, Rebecca; Kessel, Line

. The retinal vascular fractal dimension was measured using the box-counting method and compared within monozygotic and dizygotic twin pairs using Pearson correlation coefficents. Falconer´s formula and quantitative genetic models were used to determine the genetic component of variation. Results: The retinal...... for quantitative analysis of heritability. The intrapair correlation was markedly higher (0.505, p=0.0002) in monozygotic twins than in dizygotic twins (0.108, p=0.46), corresponding to a heritability h2 for the fractal dimension of 0.79. In quantitative genetic models, 54% of the variation was explained...

Contravariant gravity on Poisson manifolds and Einstein gravity

International Nuclear Information System (INIS)

Kaneko, Yukio; Watamura, Satoshi; Muraki, Hisayoshi

2017-01-01

A relation between gravity on Poisson manifolds proposed in Asakawa et al (2015 Fortschr. Phys . 63 683–704) and Einstein gravity is investigated. The compatibility of the Poisson and Riemann structures defines a unique connection, the contravariant Levi-Civita connection, and leads to the idea of the contravariant gravity. The Einstein–Hilbert-type action yields an equation of motion which is written in terms of the analog of the Einstein tensor, and it includes couplings between the metric and the Poisson tensor. The study of the Weyl transformation reveals properties of those interactions. It is argued that this theory can have an equivalent description as a system of Einstein gravity coupled to matter. As an example, it is shown that the contravariant gravity on a two-dimensional Poisson manifold can be described by a real scalar field coupled to the metric in a specific manner. (paper)

Monozygotic twins discordant for attention-deficit/hyperactivity disorder: ascertainment and clinical characteristics.

Science.gov (United States)

Sharp, Wendy S; Gottesman, Rebecca F; Greenstein, Deanna K; Ebens, Christen L; Rapoport, Judith L; Castellanos, F Xavier

2003-01-01

Nongenetic factors and phenomenology of attention-deficit/hyperactivity disorder (ADHD) were examined in monozygotic (MZ) twin pairs discordant for ADHD. Recruitment included telephone screening (n = 297 pairs), behavioral ratings obtained from parents and teachers (n = 59 pairs), and, finally, in-person assessment (n = 25 pairs; structured classroom observation, diagnostic interview, psychoeducational evaluation, birth record review, establishment of monozygosity, and anatomic brain imaging). Affected twins were further contrasted with previously studied affected singletons. Of the 25 MZ twin pairs qualifying for in-person evaluation, only 10 proved discordant for ADHD. Affected twins were mostly comparable with affected singletons on clinical measures, although fathers' self-ratings of childhood ADHD status were significantly lower in twins than in singletons. Discordance for ADHD in MZ twins appears to be ascribable to greater environmental discordance and decreased familiality. Despite these differences, affected twins were phenotypically comparable with affected singletons. Thus MZ twins discordant for ADHD, while rare, can inform research on the etiology and pathophysiology of this disorder.

Magnetic resonance in multiple sclerose twins

International Nuclear Information System (INIS)

Polman, C.H.; UitdeHaag, B.M.J.; Koetsier, C.J.; Valk, J.; Lucas, C.J.

1989-01-01

Magnetic resonance imaging (MR) examinations were performed in a series of 7 twin sets (4 monozygotic and 3 dizygotic) and one triplet set who were clinically discordant for multiple sclerosis (MS). MRI abnormalities were detected in a number of the unaffected members of the nonzygotic twin pairs. The authors discuss the possible implications of their findings for the present view on the aetiology of MS. (author). 3 refs.; 1 fig.; 1 tab

Progestogens to prevent preterm birth in twin pregnancies: an individual participant data meta-analysis of randomized trials

Directory of Open Access Journals (Sweden)

Schuit Ewoud

2012-03-01

Full Text Available Abstract Background Preterm birth is the principal factor contributing to adverse outcomes in multiple pregnancies. Randomized controlled trials of progestogens to prevent preterm birth in twin pregnancies have shown no clear benefits. However, individual studies have not had sufficient power to evaluate potential benefits in women at particular high risk of early delivery (for example, women with a previous preterm birth or short cervix or to determine adverse effects for rare outcomes such as intrauterine death. Methods/design We propose an individual participant data meta-analysis of high quality randomized, double-blind, placebo-controlled trials of progestogen treatment in women with a twin pregnancy. The primary outcome will be adverse perinatal outcome (a composite measure of perinatal mortality and significant neonatal morbidity. Missing data will be imputed within each original study, before data of the individual studies are pooled. The effects of 17-hydroxyprogesterone caproate or vaginal progesterone treatment in women with twin pregnancies will be estimated by means of a random effects log-binomial model. Analyses will be adjusted for variables used in stratified randomization as appropriate. Pre-specified subgroup analysis will be performed to explore the effect of progestogen treatment in high-risk groups. Discussion Combining individual patient data from different randomized trials has potential to provide valuable, clinically useful information regarding the benefits and potential harms of progestogens in women with twin pregnancy overall and in relevant subgroups.

Quality of life in unaffected twins discordant for affective disorder

DEFF Research Database (Denmark)

Vinberg, Maj; Bech, Per; Kyvik, Kirsten Ohm

2006-01-01

BACKGROUND: The disability and hardship associated with affective disorder is shared by the family members of affective patients and might affect the family member's quality of life. METHOD: In a cross-sectional, high-risk, case-control study, monozygotic (MZ) and dizygotic (DZ) twins with (High......-Risk twins) and without (the control group/Low-Risk twins) a co-twin history of affective disorder were identified through nationwide registers. The aim of the present study was to investigate the hypothesis that a genetic liability to affective disorder is associated with a lower perception of quality...

Generalized planar fault energies and twinning in Cu-Al alloys

Science.gov (United States)

Kibey, S.; Liu, J. B.; Johnson, D. D.; Sehitoglu, H.

2006-11-01

We report ab initio density functional theory calculations of generalized planar fault energies of fcc Cu -xAl (x =0, 5.0, and 8.3at.%) alloys. We investigate the effects of substitutional solute Al on the unstable intrinsic γus and twin γut stacking fault energies (SFEs). Our results reveal an increased tendency of Cu-Al to deform preferentially by twinning with increasing Al content, consistent with experiment. We attribute this mechanical behavior to appreciable lowering of the twinning barrier γut, along with the stable intrinsic and twin SFEs.

Gravity and Height Variations at Medicina, Italy

Science.gov (United States)

Bruni, Sara; Zerbini, Susanna; Errico, Maddalena; Santi, Efisio; Wziontek, Hartmut

2017-04-01

Since 1996, at the Medicina station, height and gravity variations are monitored continuously by means of GPS, VLBI and superconducting gravimeter (SG) data. Additionally, absolute gravity observations are performed twice a year and environmental parameters, among others water table levels, are regularly acquired. Levelling between the different monuments at the site area is also carried out repeatedly to constrain local ties in the vertical position. Two GPS systems are located very close to each other, and both are in close proximity to the VLBI antenna. Twenty years of data are now available, which allow investigating both long- and short-period height and gravity signals together with their relevant correlations. Natural land subsidence, which is well known to occur in the area, is a major component of the observed long-term behavior; however, non-linear long-period signatures are also present in the time series. On a shorter time scale, fingerprints of the water table seasonal oscillations can be recognized in the data. The Medicina site is characterized by clayey soil subjected to consolidation effects when the water table lowers during summer periods. The pillar on which the SG is installed is especially affected because of its shallow foundation, causing height decreases in the order of 2.5-3 cm for water table lowering of 2 m. This study presents a comparative analysis of the different data sets with the aim of separating mass and deformation contributions in the SG gravity record.

Dialysis for twins

DEFF Research Database (Denmark)

Gramkow, Ann-Maria; Aarup, Michael; Andersen, L. L. T.

2014-01-01

A 32-year-old woman with known stage-4 chronic kidney disease due to lupus nephritis presented with twin pregnancy after in vitro fertilization at a gestational age of 24 weeks + 3 days because of imminent preterm labour. Repeated ultrasound evaluations confirmed intrauterine growth restriction...

Twin reversed arterial perfusion sequence is more common than generally accepted

NARCIS (Netherlands)

Gemert, M.J. van; Wijngaard, J.P. van den; Vandenbussche, F.P.H.A.

2015-01-01

BACKGROUND: Approximately 75% of monozygotic twin pregnancies share one monochorionic placenta where placental anastomoses are virtually always present to connect the two fetoplacental circulations. These anastomoses cause several serious complications such as acardiac twinning. Acardiac twins lack

Genetic susceptibility to bilateral tinnitus in a Swedish twin cohort

DEFF Research Database (Denmark)

Maas, Iris Lianne; Brüggemann, Petra; Requena, Teresa

2017-01-01

PURPOSE: Genetic contributions to tinnitus have been difficult to determine due to the heterogeneity of the condition and its broad etiology. Here, we evaluated the genetic and nongenetic influences on self-reported tinnitus from the Swedish Twin Registry (STR). METHODS: Cross-sectional data from...... the STR was obtained. Casewise concordance rates (the risk of one twin being affected given that his/her twin partner has tinnitus) were compared for monozygotic (MZ) and dizygotic (DZ) twin pairs (N = 10,464 concordant and discordant twin pairs) and heritability coefficients (the proportion of the total...... variance attributable to genetic factors) were calculated using biometrical model fitting procedures. RESULTS: Stratification of tinnitus cases into subtypes according to laterality (unilateral versus bilateral) revealed that heritability of bilateral tinnitus was 0.56; however, it was 0.27 for unilateral...

Mode of birth in twins: data and reflections.

Science.gov (United States)

Reitter, A; Daviss, B A; Krimphove, M J; Johnson, K C; Schlößer, R; Louwen, F; Bisits, A

2018-02-12

Our primary objective was to compare neonatal and maternal outcomes in women with twin pregnancies, beyond 32 weeks, having a planned vaginal birth or a planned caesarean section (CS). This was a retrospective cohort study from a single tertiary centre over nine years. 534 sets of twins ≥32 + 0 weeks of gestation were included. 401 sets were planned vaginally and 133 sets were planned by CS. We compared a composite adverse perinatal outcome (perinatal mortality or serious neonatal morbidity; five minute APGAR score ≤4, neurological abnormality and need for intubation) and a composite maternal adverse outcome (major haemorrhage, trauma or infection) between the groups. There were no significant differences. Given the similarity of these results with several other larger studies of twin birth, we sought to look at reasons why there is still a rising rate of CS for twin births. We further make suggestions for keeping this rate to a sensible minimum. Impact statement What is already known on this subject? The largest randomised controlled study comparing planned vaginal birth with planned CSs for lower risk twins between 32 and 39 weeks of gestation, showed no added safety from planned CS. However, in most of the Western countries this conclusion has failed to increase the number of planned vaginal births for lower risk twins. What do the results of this study add? This observational study from a single tertiary centre provides external validation of the twin trial results in a practical day-to-day setting. It also provides insights as to how planned vaginal birth can be developed and maintained, with a key focus on safety and maternal participation in decision making. It does focus on consent and providing accurate data. What are the implications of these findings for clinical practice and/or further research? There are good grounds to encourage vaginal birth for low-risk twin pregnancies. The trend of rising caesarean rates in low-risk twin

Is nonrelativistic gravity possible?

International Nuclear Information System (INIS)

Kocharyan, A. A.

2009-01-01

We study nonrelativistic gravity using the Hamiltonian formalism. For the dynamics of general relativity (relativistic gravity) the formalism is well known and called the Arnowitt-Deser-Misner (ADM) formalism. We show that if the lapse function is constrained correctly, then nonrelativistic gravity is described by a consistent Hamiltonian system. Surprisingly, nonrelativistic gravity can have solutions identical to relativistic gravity ones. In particular, (anti-)de Sitter black holes of Einstein gravity and IR limit of Horava gravity are locally identical.

Monozygotic twins with CAPN5 autosomal dominant neovascular inflammatory vitreoretinopathy

Directory of Open Access Journals (Sweden)

Rowell HA

2012-12-01

Full Text Available Hannah A Rowell,1,2 Alexander G Bassuk,3,4 Vinit B Mahajan1,21Omics Laboratory, 2Department of Ophthalmology and Visual Sciences, 3Department of Pediatrics, 4Department of Neurology, University of Iowa, Iowa City, IA, USABackground: The purpose of this study was to describe the clinical findings in a set of monozygotic twins with autosomal dominant neovascular inflammatory vitreoretinopathy (ADNIV over a 23-year period.Methods: A pair of female twins were examined between 26 and 49 years of age. The concordance and discordance of their clinical features were determined. The CAPN5 gene was sequenced using genomic DNA.Results: Both twins of an affected father demonstrated Stage I ADNIV with mild vitreous cells and a negative b-wave on electroretinography. Genetic analysis confirmed a guanine to thymine nucleotide (c.728G>T, pArg243Leu mutation in the CAPN5 gene. Over the course of 23 years, each twin progressed to stage III disease, showing posterior uveitis, cystoid macular edema, intraocular fibrosis, early retinal neovascularization, retinal degeneration, and cataract. Disease progression varied moderately between each twin and was asymmetrical between eyes. Twin A had 20/70 and 20/125 in the right and left eye, respectively, and underwent vitrectomy surgery and intravitreal injections with bevacizumab for recurrent cystoid macular edema. Twin B maintained 20/20 and 20/40 in the right and left eye, respectively without intervention.Conclusion: There was asymmetry between the eyes and some discordance in the rate of disease progression in these monozygotic twins with ADNIV. The overall high disease concordance suggests genetic factors play a major role in clinical manifestations in CAPN5 vitreoretinopathy.Keywords: autosomal dominant neovascular inflammatory vitreoretinopathy, ADNIV, CAPN5, calpain-5, monozygotic twins

Seasonal changes, sleep length and circadian preference among twins with bipolar disorder

Directory of Open Access Journals (Sweden)

Koskenvuo Markku

2003-06-01

Full Text Available Abstract Background We aimed at studying the seasonal changes in mood and behaviour, the distribution of hospital admissions by season, and the persistence of the circadian type in twins with bipolar disorder and their healthy co-twins. Methods All Finnish like-sex twins born from 1940 to 1969 were screened for a diagnosis of bipolar type I disorder. The diagnosis was assessed with a structured research interview, and the study subjects (n = 67 filled in the Seasonal Pattern Assessment Questionnaire (SPAQ and the Morningness-Eveningness Questionnaire (MEQ. For studying the persistence of the habitual sleep length and circadian type, we used data derived from the Finnish Twin Cohort Questionnaire (FTCQ. Bipolar twins were compared with their healthy co-twins. Results Bipolar twins had greater seasonal changes in sleep length (p = 0.01 and mood (p = 0.01, and higher global seasonality scores (p = 0.03 as compared with their co-twins with no mental disorder. Sunny days (p = 0.03 had a greater positive effect on wellbeing in the bipolar than healthy co-twins. Conclusions Our results support the view that bipolar disorder is sensitive to the environmental influence in general and to the seasonal effect in specific. Exposure to natural light appears to have a substantial effect on wellbeing in twins with bipolar disorder.

Factors that affect skin aging: a cohort-based survey on twins.

Science.gov (United States)

Martires, Kathryn J; Fu, Pingfu; Polster, Amy M; Cooper, Kevin D; Baron, Elma D

2009-12-01

To identify environmental factors that correlate with skin photoaging, controlling for genetic susceptibility by using a questionnaire administered to twins. The survey collected information about each participant's Fitzpatrick type, history of skin cancer, smoking and drinking habits, and weight from a cohort of twins. Clinicians then assigned a clinical photodamage score to each participant. The annual Twins Days Festival in Twinsburg, Ohio. A voluntary cohort of twins from the general community, mostly from Ohio, Pennsylvania, and the northeastern United States. The survey was completed on a voluntary basis by sets of monozygotic (MZ) and dizygotic (DZ) twins. A total of 130 surveys taken by 65 complete twin pairs were analyzed. Skin aging was assessed using a validated photographic scale of photodamage, graded by such characteristics as wrinkling and pigmentation change. Photodamage scores among twins of a pair, whether MZ or DZ, were highly correlated (P = .92). Factors found to predict higher photodamage include history of skin cancer (P < .001), zygosity status (MZ vs DZ) (P = .001), weight (P = .02), and cigarette smoking (P = .046). Alcohol consumption was significantly associated with lower photodamage scores (P = .003). The study of twins provides a unique opportunity to control for genetic susceptibility in order to elucidate environmental influences on skin aging. The relationships found between smoking, weight, sunscreen use, skin cancer, and photodamage in these twin pairs may help to motivate the reduction of risky behaviors.

Topics in quantum gravity

International Nuclear Information System (INIS)

Lamon, Raphael

2010-01-01

succeed in solving the quantum Gauss constraint. In the second part of the thesis we introduce some aspects of phenomenological quantum gravity and their possible detectable signatures. The goal of phenomenological quantum gravity is to derive conclusions and make predictions from expected characteristics of a full theory of quantum gravity. One possibility is an energy-dependent speed of light arising from a quantized space such that the propagation time of two photons differs. However, the amount of these corrections is very small such that only cosmological distances can be considered. Gamma-ray bursts (GRB) are ideal candidates as they are short but very luminous bursts of gamma-rays taking place at distances billions of light-years away. We study GRBs detected by the European satellite INTEGRAL and develop a new method to analyze unbinned data. A χ 2 -test will provide a lower bound for quantum gravity corrections, which will be nevertheless well below the Planck mass. Then we shall study the sensibility of NASA's new satellite Fermi Gamma-ray Space Telescope and conclude that it is well suited to detect corrections. This prediction has just been confirmed when Fermi detected a very energetic photon emanating from GRB 090510 which highly constrains models with linear corrections to the speed of light. However, as it is shown at the end of this thesis, more bursts are needed in order to definitely falsify such models. (orig.)

Twin reversed arterial perfusion sequence is more common than generally accepted

NARCIS (Netherlands)

van Gemert, Martin J. C.; van den Wijngaard, Jeroen P. H. M.; Vandenbussche, Frank P. H. A.

2015-01-01

Approximately 75% of monozygotic twin pregnancies share one monochorionic placenta where placental anastomoses are virtually always present to connect the two fetoplacental circulations. These anastomoses cause several serious complications such as acardiac twinning. Acardiac twins lack a functional

Risk of Monozygotic Twins After Assisted Reproduction: A Population-Based Approach.

Science.gov (United States)

Parazzini, Fabio; Cipriani, Sonia; Bianchi, Stefano; Bulfoni, Camilla; Bortolus, Renata; Somigliana, Edgardo

2016-02-01

Recent studies have suggested that ovarian stimulation and assisted reproductive techniques (ART) may increase the frequency of monozygotic twins. In this article, we present the analysis of the estimated frequency of twin deliveries following in vitro fertilization (IVF) in Lombardy during the period 2010-2014 for a total of 450,949 pregnancies. This is a population-based study using data from the regional data base of Lombardy, a northern Italian region with a population of about 10 million inhabitants. During the considered period, a total of 461,424 single or multiple births were registered in Lombardy. After exclusion of triplets or more pregnancies, the total number of twin deliveries, in separate strata of like and unlike sex pregnancies twin deliveries, were obtained and the rate of twin deliveries was computed according to spontaneous and non-spontaneous conception and type of ART. Further, estimates of dizygotic or monozygotic twin births were calculated using Weinberg's methods. The frequency of twins deliveries was 1.24/100 deliveries after natural conception and 20.05 after assisted conception. The estimated rates of monozygotic twins was 0.45 and 0.72/100 (95% CI: 0.58-0.91) deliveries after natural and assisted conception, respectively. This difference was statistically significant (p assisted than after natural conception.

Evidence of genetic susceptibility to infectious mononucleosis: a twin study.

Science.gov (United States)

Hwang, A E; Hamilton, A S; Cockburn, M G; Ambinder, R; Zadnick, J; Brown, E E; Mack, T M; Cozen, W

2012-11-01

Infectious mononucleosis is a clinical manifestation of primary Epstein-Barr virus infection. It is unknown whether genetic factors contribute to risk. To assess heritability, we compared disease concordance in monozygotic to dizygotic twin pairs from the population-based California Twin Program and assessed the risk to initially unaffected co-twins. One member of 611 and both members of 58 twin pairs reported a history of infectious mononucleosis. Pairwise concordance in monozygotic and dizygotic pairs was respectively 12·1% [standard error (s.e.)=1·9%] and 6·1% (s.e.=1·2%). The relative risk (hazard ratio) of monozygotic compared to dizygotic unaffected co-twins of cases was 1·9 [95% confidence interval (CI) 1·1-3·4, P=0·03], over the follow-up period. When the analysis was restricted to same-sex twin pairs, that estimate was 2·5 (95% CI 1·2-5·3, P=0·02). The results are compatible with a heritable contribution to the risk of infectious mononucleosis.

Nephrolithiasis in identical twins: the impact of nature vs nurture.

Science.gov (United States)

Haleblian, George E; Cantor, David A; Sur, Roger L; Assimos, Dean G; Preminger, Glenn M

2007-09-01

To assess possible underlying metabolic abnormalities in three sets of monozygotic twins, to evaluate the interplay among the factors of kidney stone formation, a complex multifactorial process influenced by environmental, genetic and anatomical factors. Three sets of identical twins with either cystine or calcium oxalate stones were identified. Demographic data, medical histories and the results of 24-h urine testing, with samples collected on self-selected diets, were reviewed and analysed. The cystinuric twins had very similar cystine excretion rates, while stone activity was significantly more pronounced in one. Metabolic abnormalities were concordant in one set of twins with calcium oxalate stones, both being hypercalciuric and hyperuricosuric. However, metabolic abnormalities were discordant in the other pair, one twin with hypercalciuria and the other with hypocitraturia. Two of the three pairs had low urinary volume. These results support previous observations that environmental, genetic and potentially, anatomical factors play roles in kidney-stone formation. Additional controlled studies of monozygotic stone-forming twins might help to define the interplay between environmental and genetic factors, and allow the identification of susceptibility genes involved in stone generation.

Spontaneous unilateral Twin Ectopic Pregnancy: A case report

Directory of Open Access Journals (Sweden)

هادی اریا منش

2017-03-01

Full Text Available Abstract Aim & Objective: Twin pregnancy in the tube is a few and due to more frequent use of ovulatory medicine and increased maternal mortality rate. In this article, we report a case of  untitled twin ectopic pregnancy. Case study: The pregnant women was a 28 year-old  to had  a  history infertility, PCOD, Abortion and cortege,   too have one 5 years girl by CS and  Mild cramp pain in both abdominal lower quadrants and metroreghia . That have not treatment by projection. The ultra-sonography showed a twin pregnancy uterus with a moderate amount of fluid in pelvic cavity was seen. And do salpanjectimy surgery. Conclusion:  We report one Untitled Spontaneous Twin Ectopic Pregnancy,  is necessary any pregnant woman with  positive BhCG and metrorhoghia must be considered for Ectopic pregnancy. To decrease maternal mortality rate. Key words:

Two wide-angle imaging neutral-atom spectrometers (TWINS)

International Nuclear Information System (INIS)

McComas, D.J.; Blake, B.; Burch, J.

1998-01-01

Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) is a revolutionary new mission designed to stereoscopically image the magnetosphere in charge exchange neutral atoms for the first time. The authors propose to fly two identical TWINS instruments as a mission of opportunity on two widely-spaced high-altitude, high-inclination US Government spacecraft. Because the spacecraft are funded independently, TWINS can provide a vast quantity of high priority science observations (as identified in an ongoing new missions concept study and the Sun-Earth Connections Roadmap) at a small fraction of the cost of a dedicated mission. Because stereo observations of the near-Earth space environs will provide a particularly graphic means for visualizing the magnetosphere in action, and because of the dedication and commitment of the investigator team to the principles of carrying space science to the broader audience, TWINS will also be an outstanding tool for public education and outreach

The oxidative burst reaction in mammalian cells depends on gravity.

Science.gov (United States)

Adrian, Astrid; Schoppmann, Kathrin; Sromicki, Juri; Brungs, Sonja; von der Wiesche, Melanie; Hock, Bertold; Kolanus, Waldemar; Hemmersbach, Ruth; Ullrich, Oliver

2013-12-20

Gravity has been a constant force throughout the Earth's evolutionary history. Thus, one of the fundamental biological questions is if and how complex cellular and molecular functions of life on Earth require gravity. In this study, we investigated the influence of gravity on the oxidative burst reaction in macrophages, one of the key elements in innate immune response and cellular signaling. An important step is the production of superoxide by the NADPH oxidase, which is rapidly converted to H2O2 by spontaneous and enzymatic dismutation. The phagozytosis-mediated oxidative burst under altered gravity conditions was studied in NR8383 rat alveolar macrophages by means of a luminol assay. Ground-based experiments in "functional weightlessness" were performed using a 2 D clinostat combined with a photomultiplier (PMT clinostat). The same technical set-up was used during the 13th DLR and 51st ESA parabolic flight campaign. Furthermore, hypergravity conditions were provided by using the Multi-Sample Incubation Centrifuge (MuSIC) and the Short Arm Human Centrifuge (SAHC). The results demonstrate that release of reactive oxygen species (ROS) during the oxidative burst reaction depends greatly on gravity conditions. ROS release is 1.) reduced in microgravity, 2.) enhanced in hypergravity and 3.) responds rapidly and reversible to altered gravity within seconds. We substantiated the effect of altered gravity on oxidative burst reaction in two independent experimental systems, parabolic flights and 2D clinostat / centrifuge experiments. Furthermore, the results obtained in simulated microgravity (2D clinorotation experiments) were proven by experiments in real microgravity as in both cases a pronounced reduction in ROS was observed. Our experiments indicate that gravity-sensitive steps are located both in the initial activation pathways and in the final oxidative burst reaction itself, which could be explained by the role of cytoskeletal dynamics in the assembly and function

The Yoruba's cultural perspective of death with special reference to twins.

Science.gov (United States)

Olaleye-Oruene, Taiwo O

2002-06-01

To the Yoruba people of South-West Nigeria, on the West Coast of Africa, death, or transition from one level of existence to another, is well accepted as part of life. Rites of passage are seen as an opportunity for saying farewell to the deceased and seeking their continuous protection of the living members of the families. After the death of a twin, a twin statuette, symbolically representing the departed twin, also acts as a companion and solace to the living twin. This paper examines these subjects including the special rites performed for twins, the relationship of the family to the deceased and the question of reincarnation

MRI findings in multifetal pregnancies complicated by twin reversed arterial perfusion sequence (TRAP)

Energy Technology Data Exchange (ETDEWEB)

Guimaraes, Carolina V.A.; Kline-Fath, Beth M.; Linam, Leann E.; Calvo Garcia, Maria A.; Rubio, Eva I. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States); Lim, Foong-Yen [Cincinnati Children' s Hospital Medical Center, Division of Pediatric Surgery, Cincinnati, OH (United States)

2011-06-15

Twin reversed arterial perfusion sequence (TRAP) is a rare complication in multifetal monochorionic pregnancies in which a normal ''pump'' twin provides circulation to an abnormal acardiac co-twin, resulting in high-output cardiac dysfunction in the pump twin. To define fetal MRI findings of TRAP sequence. Fetal MR images were retrospectively reviewed in 35 pregnancies complicated by TRAP sequence. Abnormalities of the pump twin, acardiac twin, umbilical cord, placenta and amniotic fluid were reviewed. Acardiac twins were classified as: acephalus (51%), anceps (40%), amorphus (9%), acormus (0%). Common findings in acardiac twins include subcutaneous edema (77%), absent cardiac structures (86%), absent or abnormal thoracic cavity (100%), abnormal abdominal organs (100%), superior limbs absent (46%) or abnormal (51%), and inferior limbs present but abnormal (83%). There were pump twin findings of cardiac dysfunction in 43% and intracranial ischemic changes in 3%. Umbilical cord anomalies were present in 97%. Acardiac twins present with a predictable pattern of malformation with poorly developed superior structures, more normally formed inferior structures and absent or rudimentary heart. Although usually absent, abnormal heart structures can be seen and do not exclude TRAP sequence. Pump twins are commonly normal with exception of findings of cardiac dysfunction and possible brain ischemia. (orig.)

Gravity-matter entanglement in Regge quantum gravity

International Nuclear Information System (INIS)

Paunković, Nikola; Vojinović, Marko

2016-01-01

We argue that Hartle-Hawking states in the Regge quantum gravity model generically contain non-trivial entanglement between gravity and matter fields. Generic impossibility to talk about “matter in a point of space” is in line with the idea of an emergent spacetime, and as such could be taken as a possible candidate for a criterion for a plausible theory of quantum gravity. Finally, this new entanglement could be seen as an additional “effective interaction”, which could possibly bring corrections to the weak equivalence principle. (paper)

Sirenomelia type VI (sympus apus) in one of dizygotic twins at Chiang Mai University Hospital.

Science.gov (United States)

Nokeaingtong, Kwannapas; Kaewchai, Sirirat; Visrutaratna, Pannee; Khuwuthyakorn, Varangthip

2015-05-14

Those born with sirenomelia, a rare congenital anomaly, have features resembling a mermaid. Characteristics of sirenomelia are a single lower limb, sacral and pelvic bone defects, and anorectal and urogenital malformations. There is an increased incidence of sirenomelia in males and twins. This case was a preterm male, dizygotic twin and product of in vitro fertilisation. The baby was born by caesarean section due to breech presentation. He was found to have a fused lower extremity and absent external genitalia and anus. The baby passed away shortly after birth due to severe respiratory failure. Radiographic findings showed small lung volume and pneumothoraces. There were multiple segmental fusions of the vertebrae. Single femur and single tibia were presented in a fused lower limb. Autopsy demonstrated large intestinal atresia, intra-abdominal testes, absence of kidney, ureter and bladder, single umbilical artery, agenesis of blood vessels at lower extremity and agenesis of sacrum and coccyx. 2015 BMJ Publishing Group Ltd.

Lovelock gravities from Born-Infeld gravity theory

Science.gov (United States)

Concha, P. K.; Merino, N.; Rodríguez, E. K.

2017-02-01

We present a Born-Infeld gravity theory based on generalizations of Maxwell symmetries denoted as Cm. We analyze different configuration limits allowing to recover diverse Lovelock gravity actions in six dimensions. Further, the generalization to higher even dimensions is also considered.

Modeling the effect of neighboring grains on twin growth in HCP polycrystals

Science.gov (United States)

Kumar, M. Arul; Beyerlein, I. J.; Lebensohn, R. A.; Tomé, C. N.

2017-09-01

In this paper, we study the dependence of neighboring grain orientation on the local stress state around a deformation twin in a hexagonal close packed (HCP) crystal and its effects on the resistance against twin thickening. We use a recently developed, full-field elasto-visco-plastic formulation based on fast Fourier transforms that account for the twinning shear transformation imposed by the twin lamella. The study is applied to Mg, Zr and Ti, since these HCP metals tend to deform by activation of different types of slip modes. The analysis shows that the local stress along the twin boundary are strongly controlled by the relative orientation of the easiest deformation modes in the neighboring grain with respect to the twin lamella in the parent grain. A geometric expression that captures this parent-neighbor relationship is proposed and incorporated into a larger scale, mean-field visco-plastic self-consistent model to simulate the role of neighboring grain orientation on twin thickening. We demonstrate that the approach improves the prediction of twin area fraction distribution when compared with experimental observations.

Euler–Chern–Simons gravity from Lovelock–Born–Infeld gravity

OpenAIRE

Izaurieta, F.; Rodriguez, E.; Salgado, P.

2004-01-01

In the context of a gauge theoretical formulation, higher dimensional gravity invariant under the AdS group is dimensionally reduced to Euler-Chern-Simons gravity. The dimensional reduction procedure of Grignani-Nardelli [Phys. Lett. B 300, 38 (1993)] is generalized so as to permit reducing D-dimensional Lanczos Lovelock gravity to d=D-1 dimensions.

Twinning structures in near-stoichiometric lithium niobate single crystals

International Nuclear Information System (INIS)

Yao, Shuhua; Chen, Yanfeng

2010-01-01

A near-stoichiometric lithium niobate single crystal has been grown by the Czochralski method in a hanging double crucible with a continuous powder supply system. Twins were found at one of the three characteristic growth ridges of the as-grown crystal. The twin structure was observed and analyzed by transmission synchrotron topography. The image shifts ΔX and ΔY in the transmission synchrotron topograph were calculated for the 3 anti 2 anti 12 and 0 anti 222 reflections based on results from high-resolution X-ray diffractometry. It is confirmed that one of the {01 anti 1 anti 2} m planes is the composition face of the twin and matrix crystals. The formation mechanism of these twins is discussed. (orig.)

Pygopagus Conjoined Twins: A Neurophysiologic Intraoperative Monitoring Schema.

Science.gov (United States)

Cromeens, Barrett P; McKinney, Jennifer L; Leonard, Jeffrey R; Governale, Lance S; Brown, Judy L; Henry, Christina M; Levitt, Marc A; Wood, Richard J; Besner, Gail E; Islam, Monica P

2017-03-01

Conjoined twins occur in up to 1 in 50,000 live births with approximately 18% joined in a pygopagus configuration at the buttocks. Twins with this configuration display symptoms and carry surgical risks during separation related to the extent of their connection which can include anorectal, genitourinary, vertebral, and neural structures. Neurophysiologic intraoperative monitoring for these cases has been discussed in the literature with variable utility. The authors present a case of pygopagus twins with fused spinal cords and imperforate anus where the use of neurophysiologic intraoperative monitoring significantly impacted surgical decision-making in division of these critical structures.

Cosmology in Mirror Twin Higgs and neutrino masses

Science.gov (United States)

Chacko, Zackaria; Craig, Nathaniel; Fox, Patrick J.; Harnik, Roni

2017-07-01

We explore a simple solution to the cosmological challenges of the original Mirror Twin Higgs (MTH) model that leads to interesting implications for experiment. We consider theories in which both the standard model and mirror neutrinos acquire masses through the familiar seesaw mechanism, but with a low right-handed neutrino mass scale of order a few GeV. In these νMTH models, the right-handed neutrinos leave the thermal bath while still relativistic. As the universe expands, these particles eventually become nonrelativistic, and come to dominate the energy density of the universe before decaying. Decays to standard model states are preferred, with the result that the visible sector is left at a higher temperature than the twin sector. Consequently the contribution of the twin sector to the radiation density in the early universe is suppressed, allowing the current bounds on this scenario to be satisfied. However, the energy density in twin radiation remains large enough to be discovered in future cosmic microwave background experiments. In addition, the twin neutrinos are significantly heavier than their standard model counterparts, resulting in a sizable contribution to the overall mass density in neutrinos that can be detected in upcoming experiments designed to probe the large scale structure of the universe.

Aging and communication in the twin paradox

International Nuclear Information System (INIS)

De Wolf, David A

2016-01-01

The twin paradox of the special theory of relativity has given rize to a large body of literature discussing its implications. In its standard form, the traveler changes velocity only at the destination of the trip, so that he appears to perceive an improbably instantaneous and non-continuous change in age of the stationary twin. In this work, a smooth velocity/acceleration profile is used that allows the abrupt velocity-change case as a limit. All gravitational effects are ignored in this treatment. Aside from mutual perception of simultaneous clock times in an accelerating frame, constant communication of clock times between the twins by means of (digital) light signals is shown to be possible, in principle if not in practice. (paper)

Gravity

CERN Document Server

Gamow, George

2003-01-01

A distinguished physicist and teacher, George Gamow also possessed a special gift for making the intricacies of science accessible to a wide audience. In Gravity, he takes an enlightening look at three of the towering figures of science who unlocked many of the mysteries behind the laws of physics: Galileo, the first to take a close look at the process of free and restricted fall; Newton, originator of the concept of gravity as a universal force; and Einstein, who proposed that gravity is no more than the curvature of the four-dimensional space-time continuum.Graced with the author's own draw

Twinning anisotropy of tantalum during nanoindentation

Energy Technology Data Exchange (ETDEWEB)

Goel, Saurav, E-mail: S.GOEL@qub.ac.uk [School of Mechanical and Aerospace Engineering, Queen' s University, Belfast, BT9 5AH (United Kingdom); Beake, Ben [Micro Materials Limited, Willow House, Yale Business Village, Ellice Way, Wrexham LL13 7YL (United Kingdom); Dalton Research Institute, Manchester Metropolitan University, Manchester, M15GD (United Kingdom); Chan, Chi-Wai [School of Mechanical and Aerospace Engineering, Queen' s University, Belfast, BT9 5AH (United Kingdom); Haque Faisal, Nadimul [School of Engineering, Robert Gordon University, Garthdee Road, Aberdeen AB10 7GJ (United Kingdom); Dunne, Nicholas [School of Mechanical and Aerospace Engineering, Queen' s University, Belfast, BT9 5AH (United Kingdom)

2015-03-11

Unlike other BCC metals, the plastic deformation of nanocrystalline Tantalum (Ta) during compression is regulated by deformation twinning. Whether or not this twinning exhibits anisotropy was investigated through simulation of displacement-controlled nanoindentation test using molecular dynamics (MD) simulation. MD data was found to correlate well with the experimental data in terms of surface topography and hardness measurements. The mechanism of the transport of material was identified due to the formation and motion of prismatic dislocations loops (edge dislocations) belonging to the 1/2〈111〉 type and 〈100〉 type Burgers vector family. Further analysis of crystal defects using a fully automated dislocation extraction algorithm (DXA) illuminated formation and migration of twin boundaries on the (110) and (111) orientation but not on the (010) orientation and most importantly after retraction all the dislocations disappeared on the (110) orientation suggesting twinning to dominate dislocation nucleation in driving plasticity in tantalum. A significant finding was that the maximum shear stress (critical Tresca stress) in the deformation zone exceeded the theoretical shear strength of Ta (Shear modulus/2π~10.03 GPa) on the (010) orientation but was lower than it on the (110) and the (111) orientations. In light of this, the conventional lore of assuming the maximum shear stress being 0.465 times the mean contact pressure was found to break down at atomic scale.

Prenatal Sonographic Diagnosis of Acardiac Twins

Energy Technology Data Exchange (ETDEWEB)

Kim, Jeong Ah; Song, Mi Jin [Cheil General Hospital, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

2006-09-15

This study was performed to present the prenatal sonographic findings and the associated abnormalities of acardiac twins. Seven cases of acardiac twins were reviewed retrospectively. Prenatal ultrasonography was performed in all patients at a gestational age between 12 and 27 weeks (mean 17.6 weeks). Autopsy was performed in four cases. The sonographic and autopsy findings were reviewed to report the associated abnormalities of the acardiac and donor fetuses. The diagnosis of acardiac twins was made on the basis of ultrasonography (n=6) or autopsy (n=1). The associated abnormalities of the acardiac fetuses were single umbilical artery (SUA) (n=5), abdominal wall defect (n=4), club feet (n=4), scoliosis (n=1), cleft lip and palate (n=1), digital anomaly (n=1), and umbilical cord cyst (n=1). In four of the donor fetuses, sonographic abnormalities were found. Autopsy was performed in three of the four cases to reveal hydropic change (n=2), diaphragmatic hernia (n=1) and multiple structural abnormalities of interventricular septal defect, polydactyly, club feet and SUA (n=1). Intrauterine fetal death occurred in five donors and follow-up was lost in the remaining two. Meticulous sonography enables the diagnosis of acardiac twins at an early gestational age and can reveal the associated abnormalities of the donor fetus as well as the acardiac fetus

Prenatal Sonographic Diagnosis of Acardiac Twins

International Nuclear Information System (INIS)

Kim, Jeong Ah; Song, Mi Jin

2006-01-01

This study was performed to present the prenatal sonographic findings and the associated abnormalities of acardiac twins. Seven cases of acardiac twins were reviewed retrospectively. Prenatal ultrasonography was performed in all patients at a gestational age between 12 and 27 weeks (mean 17.6 weeks). Autopsy was performed in four cases. The sonographic and autopsy findings were reviewed to report the associated abnormalities of the acardiac and donor fetuses. The diagnosis of acardiac twins was made on the basis of ultrasonography (n=6) or autopsy (n=1). The associated abnormalities of the acardiac fetuses were single umbilical artery (SUA) (n=5), abdominal wall defect (n=4), club feet (n=4), scoliosis (n=1), cleft lip and palate (n=1), digital anomaly (n=1), and umbilical cord cyst (n=1). In four of the donor fetuses, sonographic abnormalities were found. Autopsy was performed in three of the four cases to reveal hydropic change (n=2), diaphragmatic hernia (n=1) and multiple structural abnormalities of interventricular septal defect, polydactyly, club feet and SUA (n=1). Intrauterine fetal death occurred in five donors and follow-up was lost in the remaining two. Meticulous sonography enables the diagnosis of acardiac twins at an early gestational age and can reveal the associated abnormalities of the donor fetus as well as the acardiac fetus

Shear at Twin Domain Boundaries in YBa2Cu3O7-x

Science.gov (United States)

Caldwell, W. A.; Tamura, N.; Celestre, R. S.; MacDowell, A. A.; Padmore, H. A.; Geballe, T. H.; Koster, G.; Batterman, B. W.; Patel, J. R.

2004-05-01

The microstructure and strain state of twin domains in YBa2Cu3O7-x are discussed based upon synchrotron white-beam x-ray microdiffraction measurements. Intensity variations of the fourfold twin splitting of Laue diffraction peaks are used to determine the twin domain structure. Strain analysis shows that interfaces between neighboring twin domains are strained in shear, whereas the interior of these domains are regions of low strain. These measurements are consistent with the orientation relationships of twin boundaries within and across domains and show that basal plane shear stresses can exceed 100MPa where twin domains meet. Our results support stress field pinning of magnetic flux vortices by twin domain boundaries.

One-dimensional pulse-flow modeling of a twin-scroll turbine

International Nuclear Information System (INIS)

Chiong, M.S.; Rajoo, S.; Romagnoli, A.; Costall, A.W.; Martinez-Botas, R.F.

2016-01-01

This paper presents a revised one-dimensional (1D) pulse flow modeling of twin-scroll turbocharger turbine under pulse flow operating conditions. The proposed methodology in this paper provides further consideration for the turbine partial admission performance during model characterization. This gives rise to significant improvement on the model pulse flow prediction quality compared to the previous model. The results show that a twin-scroll turbine is not operating at full admission throughout the in-phase pulse flow conditions. Instead, they are operating at unequal admission state due to disparity in the magnitude of turbine inlet flow. On the other hand, during out-of-phase pulse flow, a twin-scroll turbine is working at partial admission state for majority of the pulse cycle. An amended mathematical correlation in calculating the twin-scroll turbine partial admission characteristics is also presented in the paper. The impact of its accuracy on the pulse flow model prediction is explored. - Highlights: • Paper presents a 1D modeling for twin-scroll turbine under pulsating flow. • Predicted pulse pressure propagation is in good agreement with experimental data. • A methodology is proposed to consider the turbine partial admission performance. • Prediction shows twin-scroll turbine operates at unequal admission during in-phase flow. • During out-of-phase flow a twin-scroll turbine mainly operates at partial admission.

A prospective study of twinning and perinatal mortality in urban Guinea-Bissau

DEFF Research Database (Denmark)

Bjerregaard-Andersen, Morten; Lund, Najaaraq; Jepsen, Frida Staarup

2012-01-01

ABSTRACT: BACKGROUND: Despite twinning being common in Africa, few prospective twin studies have been conducted. We studied twinning rate, perinatal mortality and the clinical characteristics of newborn twins in urban Guinea-Bissau. METHODS: The study was conducted at the Bandim Health Project (BHP......), a health and demographic surveillance site in Bissau, the capital of Guinea-Bissau. The cohort included all newborn twins delivered at the National Hospital Simao Mendes and in the BHP study area during the period September 2009 to August 2011 as well as singleton controls from the BHP study area. Data...... regarding obstetric history and pregnancy were collected at the hospital. Live children were examined clinically. For a subset of twin pairs zygosity was established by using genetic markers. RESULTS: Out of the 5262 births from mothers included in the BHP study area, 94 were twin births, i.e. a community...

Birth weight centiles by gestational age for twins born in south India.

Science.gov (United States)

Premkumar, Prasanna; Antonisamy, Belavendra; Mathews, Jiji; Benjamin, Santhosh; Regi, Annie; Jose, Ruby; Kuruvilla, Anil; Mathai, Mathews

2016-03-24

Birth weight centile curves are commonly used as a screening tool and to assess the position of a newborn on a given reference distribution. Birth weight of twins are known to be less than those of comparable singletons and twin-specific birth weight centile curves are recommended for use. In this study, we aim to construct gestational age specific birth weight centile curves for twins born in south India. The study was conducted at the Christian Medical College, Vellore, south India. The birth records of all consecutive pregnancies resulting in twin births between 1991 and 2005 were reviewed. Only live twin births between 24 and 42 weeks of gestation were included. Birth weight centiles for gestational age were obtained using the methodology of generalized additive models for location, scale and shape (GAMLSS). Centiles curves were obtained separately for monochorionic and dichorionic twins. Of 1530 twin pregnancies delivered during the study period (1991-2005), 1304 were included in the analysis. The median gestational age at birth was 36 weeks (1st quartile 34, 3rd quartile 38 weeks). Smoothed percentile curves for birth weight by gestational age increased progressively till 38 weeks and levels off thereafter. Compared with dichorionic twins, monochorionic twins had lower birth weight for gestational age from after 27 weeks. We provide centile values of birth weight at 24 to 42 completed weeks of gestation for twins born in south India. These charts could be used both in routine clinical assessments and epidemiological studies.

Lower dimensional gravity

International Nuclear Information System (INIS)

Brown, J.D.

1988-01-01

This book addresses the subject of gravity theories in two and three spacetime dimensions. The prevailing philosophy is that lower dimensional models of gravity provide a useful arena for developing new ideas and insights, which are applicable to four dimensional gravity. The first chapter consists of a comprehensive introduction to both two and three dimensional gravity, including a discussion of their basic structures. In the second chapter, the asymptotic structure of three dimensional Einstein gravity with a negative cosmological constant is analyzed. The third chapter contains a treatment of the effects of matter sources in classical two dimensional gravity. The fourth chapter gives a complete analysis of particle pair creation by electric and gravitational fields in two dimensions, and the resulting effect on the cosmological constant

Birth weight, sex, and celiac disease: a nationwide twin study

Directory of Open Access Journals (Sweden)

Kuja-Halkola R

2017-11-01

Full Text Available Ralf Kuja-Halkola,1 Benjamin Lebwohl,1,2 Jonas Halfvarson,3 Louise Emilsson,4–6 Patrik K Magnusson,1 Jonas F Ludvigsson1,2,7,8 1Department Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; 2Department of Medicine, Celiac Disease Center, Columbia University Medical Center, Columbia University, New York, NY, USA; 3Department of Gastroenterology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden; 4Department of Health Management and Health Economy, Institute of Health and Society, University of Oslo, Oslo, Norway; 5Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA; 6Centre for Clinical Research, Vårdcentralen Värmlands Nysäter, County Council of Värmland, Värmland, 7Department of Pediatrics, Örebro University Hospital, Örebro, Sweden; 8Division of Epidemiology and Public Health, School of Medicine, City Hospital, University of Nottingham, Nottingham, UK Objective: Earlier research suggests that birth weight may be associated with celiac disease (CD, but the direction of association has been unclear potentially due to confounding effect from genetic and intrafamilial factors. Through within-twin analyses, we aimed to minimize confounding effects such as twins that share genetic and early environmental exposures.Materials and methods: Using the Swedish Twin Registry, we examined the birth weight of 146,830 twins according to the CD status. CD was defined as having villous atrophy according to a small intestinal biopsy reports.Results: The prevalence of diagnosed CD was 0.5% (n=669, and we included 407 discordant pairs of CD–non-CD twins. Comparing the 669 CD patients with non-CD twins, the association between birth weight and future CD was not statistically significant (odds ratio [OR] per 1000 g increase in birth weight: 1.16; 95% confidence interval [CI]=0.97–1.38. In males, the association was positive and statistically significant (OR=1.50; 95% CI

Cord entanglement in monoamniotic twin pregnancies

DEFF Research Database (Denmark)

Lyndrup, J; Schouenborg, Lars Øland

1987-01-01

Monoamniotic twin pregnancy involves a heavy risk of fatal umbilical cord entanglement. Two cases are reported. In the first case, both twins were found dead in the 36th week, and the monoamnionicity was recognized at birth. In the second case, the monoamnionicity was discovered during an ultraso...... an ultrasound examination, and cord entanglement was suspected in the 35th week on the basis of a non-stress test (NST) with variable decelerations. Cesarean section was performed and two healthy children were delivered....

Screening and Invasive Testing in Twins

Directory of Open Access Journals (Sweden)

Giovanni Monni

2014-07-01

Full Text Available Prenatal screening and testing for trisomy 21 in twin pregnancies poses a number of challenges: the exact estimate of the a priori risk of trisomy 21, the choice of prenatal screening test and/or invasive techniques to employ for the diagnosis and the impact of the result on the options of treatment in case of discordant results within a twin pair or among multiples. These different aspects are discussed below while recognizing that many issues remain unresolved.

Pelvic ventral hernia repair in a pygopagus conjoint twin | Bhullar ...

African Journals Online (AJOL)

Pelvic ventral hernia repair in a surviving conjoint twin with multiple congenital anomalies that make surgery a challenge. Conjoint twins are a rare. The incidence is reported to be in the range of 1/50 000 to 1/100 000 live births. Of the conjoint twins, 40% are stillborn and an additional one-third die within 24 h of birth.