Light Twin Research Articles

First-order phase transitions in Twin Higgs models

We revisit phase transitions in Twin Higgs (TH) models. We show that strong first-order phase transitions (FOPTs) can occur provided that appropriate source of ℤ2 symmetry breaking between the twin and Standard Model (SM) sectors is present. We found FOPTs in two classes of models. First: with hard ℤ2 breaking in the scalar potential allowing for FOPT. Second: with ℤ2 broken by enhanced Yukawa couplings of twin leptons. We also considered supersymmetric UV completion of the second scenario with light sleptons. The signal of gravitational waves produced during these phase transitions is typically small but can be close to the reach of AEDGE and Einstein Telescope in the case of the FOPT induced by light twin sleptons. Our results open a way to generate SM baryon asymmetry in TH models.

The effects of intrauterine growth on physical and intellectual development of one-year-old infants: a study on monochorionic twins with selective intrauterine growth restriction

This study aimed to evaluate physical and intellectual development of one-year-old infants of monochorionic twins with selective intrauterine growth restriction (sIUGR). A total of 31 pairs of sIUGR twins ageing 1 year old were included in the study. Each pair of sIUGR twins was divided into low birthweight-twin group (L-twin group) and high birthweight-twin group (H-twin group) according to twins’ birthweight. The differences in height, weight, head circumstance and body mass index (BMI) in each stage were statistically significant for all measures from birth until 1 year old (p < .05), and there was a disappointed catch-up growth in lighter twins. Psychomotor development index (PDI) and mental development index (MDI) at 1 year old were significantly different between the two groups (p < .05). Stepwise regression analysis showed that the effects of weight on both PDI and MDI were statistically significant (p < .05). Intrauterine growth inconsistencies in monochorionic twins with sIUGR persist until the first year of life and affect low-birthweight infants’ physical and intellectual development. Impact Statement What is already known on this subject? Selective intrauterine growth restriction in monochorionic twins increases the risks of intrauterine foetal demise, preterm birth, caesarean delivery and adverse neonatal outcomes, especially in the smaller foetus. What do the results of this study add? Previous studies have concentrated on the clinical management of sIUGR, while little attention has been paid to the growth and development of twins after birth. Given the adverse neurobiological effects of suboptimal nutrition on the brain development, it is important to determine whether IUGR causes long-term cognitive deficits and physical retardation. The current study has assessed the physical and intellectual development of one-year-old infants of monochorionic twins with sIUGR. What are the implications of these findings for clinical practice and/or further research? Intrauterine growth inconsistencies in monochorionic twins with sIUGR persist until the first year of life and affect low-birthweight infants’ physical and intellectual development. Further research on the longer-term effects of sIUGR is needed.

Layout and testing of a serial hybrid electric powertrain for a light twin demonstrator platform

The Project “RS hybrid 1.0” funded by the LuFo Program of the German BMWi is being executed in order to develop and investigate a serial hybrid electric powertrain to be used in a light twin aircraft, that could be exclusively operated on two electric motors. The powertrain includes a generator system, that provides energy to all power sinks like propulsors, batteries and also covers the low voltage demand of the aircraft. In the frame of this project, all necessary components are developed including the electric propulsion units, the hybrid generator system, battery modules, and DC-Link and associated subsystems.Everything is assembled in an iron bird testbed to be able to run the powertrain in an isolated fashion, to screen for potential issues and to measure operational data. Furthermore, a comprehensive control logic for the overall system and safety management of the powertrain is being developed and tested.

Light‐Ferroic Interaction in Hybrid Organic–Inorganic Perovskites

AbstractGiven the remarkable performance of hybrid organic–inorganic perovskites (HOIPs) in solar cells, light emitters, and photodetectors, the quest to advance the fundamental understanding of the photophysical properties in this class of materials remains highly relevant. Recently, the discovery of ferroic twin domains in HOIPs has renewed the debate of the ferroic effects on optoelectric processes. This work explores the interaction between light and ferroic twin domains in CH3NH3PbI3. Due to strain and chemical inhomogeneities, photogenerated electrons and holes show a preferential motion in the ferroelastic twin domains. Density functional theory (DFT) shows that electrons and holes result in lattice expansion in CH3NH3PbI3 differently. Hence, light generates strain in the ferroelastic domains due to preferential photocarrier motion, leading to a screening of strain variation. X‐ray diffraction studies verify the DFT simulations and reveal that the photoinduced strain is light intensity dependent, and the photoexcitation is a prerequisite of inducing strain by light. This work extends the fundamental understanding of light‐ferroic interaction and offers guidance for developing functional devices.

Discovering the twin Higgs boson with displaced decays

The Twin Higgs mechanism keeps the scalar sector of the Standard Model (SM) natural while remaining consistent with the non-observation of new colored particles at the Large Hadron Collider (LHC). In this construction the heavy twin Higgs boson provides a portal between the SM particles and the twin sector, but is quite challenging to discover at colliders. In the Fraternal Twin Higgs setup, where light twin quarks are absent, we study a novel discovery channel for the heavy twin Higgs boson by considering its decay to a pair of light Higgs bosons, one of which subsequently decays to glueball states in the twin sector, leading to displaced vertex signatures. We estimate the sensitivity of existing LHC searches in this channel, and assess the discovery potential of the high luminosity (HL) LHC. We show that the glueballs probed by these searches are outside the sensitivity of existing searches for exotic decays of the light Higgs boson. In addition, we demonstrate that the displaced signals we consider probe a region of heavy Higgs masses beyond the reach of prompt signals. We also comment on the possibility of probing the input parameters of the microscopic physics and providing a way to test the Twin Higgs mechanism with this channel.

Cognitive outcome in childhood of birth weight discordant monochorionic twins: the long-term effects of fetal growth restriction

AimIntrauterine growth restriction (IUGR) is associated with poorer outcomes in later life. We used a monochorionic twin model with IUGR in one twin to determine its impact on growth and...

Placental pathology in birth weight discordant monochorionic and dichorionic twins

Identification of placental parenchymal lesions (PPL) associated with birth weight (BW) discordance will be helpful in understanding the pathogenesis of BW discordance in twins. The aim of this study was to evaluate such association in monochorionic (MC) and dichorionic (DC) twins. This was a single centre, prospective study of placentas of consecutive twin deliveries. Gross and microscopic examination of placentas were done according to a protocol. Association of PPL count with the degree of BW discordance and the significance of the presence of each PPL in the lighter twin (LT) in comparison to the heavier twin (HT) were analysed. Of the 92 placentas studied 57.6% were DC and 42.4% were MC. Significant BW discordance was present in 28% (n=39) of MC and 26% (n=53) of DC twins. There was a positive correlation with the PPL count of the LT and the mean BW discordance in both MC (p=0.032) and DC twins (p=0.043). Increased incidence of distal villous hypoplasia in the placental territory of the LT in comparison to the HT was statistically significant in BW-discordant DC twins (P=0.04) and in both BW-concordant and BW-discordant MC twins (p=0.02 and p=0.03 respectively). In conclusion, this single centre prospective study showed a strong association between the PPL count and the degree of BW discordance in both MC and DC twins. Increased incidence of distal villous hypoplasia in the placental territory of the LT in comparison to the HT was statistically significant.

Gamma-rays from dark showers with twin Higgs models

We consider a twin WIMP scenario whose twin sector contains a full dark copy of the SM hadrons, where the lightest twin particles are twin pions. By analogy to the standard WIMP paradigm, the dark matter (DM) freezes out through twin electroweak interactions, and annihilates into a dark shower of light twin hadrons. These are either stable or decay predominantly to standard model (SM) photons. We show that this ‘hadrosymmetric’ scenario can be consistent with all applicable astrophysical, cosmological and collider constraints. In order to decay the twin hadrons before the big-bang nucleosynthesis epoch, an additional portal between the SM and twin sector is required. In most cases we find this additional mediator is within reach of either the LHC or future intensity frontier experiments. Furthermore, we conduct simulations of the dark shower and consequent photon spectra. We find that fits of these spectra to the claimed galactic center gamma-ray excess seen by Fermi -LAT non-trivially coincide with regions of parameter space that both successfully generate the observed DM abundance and exhibit minimal fine-tuning.

Asymmetric twin Dark Matter

We study a natural implementation of Asymmetric Dark Matter in Twin Higgs models. The mirroring of the Standard Model strong sector suggests that a twin baryon with mass around 5 GeV is a natural Dark Matter candidate once a twin baryon number asymmetry comparable to the SM asymmetry is generated. We explore twin baryon Dark Matter in two different scenarios, one with minimal content in the twin sector and one with a complete copy of the SM, including a light twin photon. The essential requirements for successful thermal history are presented, and in doing so we address some of the cosmological issues common to many Twin Higgs models. The required interactions we introduce predict signatures at direct detection experiments and at the LHC.

Design, implementation and flight testing of advanced RNP to SBAS LPV approaches in Germany

The recent publication of the advanced Required Navigation Performance (RNP) specifications enable constantly precise aircraft path guidance without demanding expensive equipment and crew certification from the operator. Combined with the operational roll-out of satellite based regional augmentation for Global Navigation Satellite Systems (GNSS), it enables new possibilities such as implementing instrument approach procedures at airports, whose location previously forbade such. Here, we design and flight test two advanced RNP procedures at the airports of Saarbrücken and Egelsbach containing a fixed radius turn which terminates at the final approach fix of a 3D guided final. Results show that the track can be followed with a precision of below 0.1 nautical miles both in manual and in automatic flight with a light piston twin aircraft and with a fast business jet. Effectively, the procedures presented in this paper decouple Saarbrücken airport from French airspace and Egelsbach airport from the high density traffic of the Frankfurt (Main) International control zone.

Twin Higgs WIMP dark matter

Dark matter (DM) without a matter asymmetry is studied in the context of twin Higgs (TH) theories in which the LHC naturalness problem is addressed. These possess a twin sector related to the Standard Model (SM) by a (broken) ${\mathbb{Z}}_{2}$ symmetry, and interacting with the SM via a specific Higgs portal. We focus on the minimal realization of the TH mechanism, the fraternal twin Higgs, with only a single generation of twin quarks and leptons, and the $SU(3{)}^{\ensuremath{'}}\ifmmode\times\else\texttimes\fi{}SU(2{)}^{\ensuremath{'}}$ gauge group. We show that a variety of natural twin-WIMP DM candidates are present (directly linked to the weak scale by naturalness), the simplest and most attractive being the ${\ensuremath{\tau}}^{\ensuremath{'}}$ lepton with a mass ${m}_{{\ensuremath{\tau}}^{\ensuremath{'}}}&gt;{m}_{\text{Higgs}}/2$, although spin-1 ${W}^{\ensuremath{'}\ifmmode\pm\else\textpm\fi{}}$ DM and multicomponent DM are also possible (twin baryons are strongly disfavored by tuning). We consider in detail the dynamics of the possibly (meta)stable glueballs in the twin sector, the nature of the twin QCD phase transition, and possible new contributions to the number of relativistic degrees of freedom, $\mathrm{\ensuremath{\Delta}}{N}_{\mathrm{eff}}$. Direct detection signals are below current bounds but accessible in near-future experiments. Indirect detection phenomenology is rich and requires detailed studies of twin hadronization and fragmentation to twin glueballs and quarkonia and their subsequent decay to SM, and possible light twin sector states.

111. The utility of video EEG in very early prematurity: A case of twin babies

Neonatal seizures occurring in severe prematurity are poorly described in the literature and extremely rare (Scher, 1993). Cases report: We report a couple of monochorionic diamniotic twins born at 27 gestational weeks suffering of foeto-fetal transfusion. Birth weight was respectively of 500 g and 890 g. Both were recorded with conventional multichannel video EEG integrated with two channels EEG monitoring located in temporo-occipital areas. The heavier twin showed clinically suspected seizures consisting of repetitive upper limbs movements and treadling movements of lower limbs associated with asymmetrical left posture. The lighter twin had ischemic hemorrhagic area in right occipital zone and left parieto-temporal-occipital zone documented with trans fontanellar ultrasounds, but not clinical suspicion of seizures. Video EEG and aEEG monitoring showed a normal pattern in the heavier twin, whereas in the lighter one the EEG showed periods of paroxysmal delta activity which were interpreted as electrical seizures. These data confirm the utility of EEG monitoring in the detection of subclinical seizures and in the differential diagnosis of not epileptic paroxysmal motor phenomena occurring in neonates born at extremely low gestational age.

Cord blood level of insulin-like growth factor-1 and IGF binding protein-3 in monochorionic twins.

Insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) are known to modulate fetal growth but their role in intrauterine growth of monochorionic twins (MCT) has not been studied. Cord venous blood was collected directly after birth. IGF-1 and IGFBP-3 in the cord venous blood were quantified by radioimmunoassay. Birth weights (BWs) were obtained electronically. Placentas were examined for chorionicity. Cord blood was collected in 37 pairs of MCT (15 pairs were males). BWs ranged from 564 to 3240 g, and gestational ages (GAs) were between 24 weeks and 39 weeks. There was a correlation between BW and cord venous blood IGFBP-3 concentration (r = 0.28, p = 0.015), but not between BW and cord venous blood IGF-1 level. There was no difference in IGF-1 between the heavier twins (30.8 ± 61.8 ng/mL) and lighter twins (33.2 ± 63.7 ng/mL), but a trend (p = 0.096) of higher IGFBP-3 level was demonstrated in heavier twins (3.14 ± 1.23 μg/mL) than in lighter twins (2.71 ± 1.19 μg/mL). The IGFBP-3 levels were higher (p = 0.042) in female twins (3.20 ± 1.33 μg/mL) than in male twins (2.64 ± 1.04 μg/mL). The IGF-1 level of the heavier twins correlated significantly to their lighter co-twin (r = 0.73, p < 0.001). Our data showed that cord venous blood IGF-1 level might be controlled mainly by genetic factors. IGFBP-3 might play an important role in fetal growth.

A new reconstructing algorithm for removing polarization effect of incident X-ray source and twin images in X-ray fluorescence holography

This paper discusses the influence of the polarization of incident X-vay on the reconstructed atomic image by numerical simulation and reconstruction, using a crystalstructure composed of 27 Fe atoms arranged in a cubic lattice as the model. Calculated results show that the choice of polarization is crucial for the atom observability. This paper proposes a new reconstructing algorithm which can eliminate the polarization effect of incident X-ray source and twin images inherent to holography at the same time. Numerical simulation and reconstruction results show that the reconstructing algorithm is effective and can be used to eliminate the influence of polarization of incident light source and twin image in experiments.

Birth Weight and Attention-Deficit/Hyperactivity Symptoms in Childhood and Early Adolescence: A Prospective Swedish Twin Study

To determine whether low birth weight increases the risk of attention-deficit/hyperactivity disorder (ADHD) in childhood and early adolescence. In a population-based sample of 1,480 twin pairs born in the period 1985-1986 ascertained from the Swedish Twin Registry, birth weight was collected prospectively through the Medical Birth Registry. ADHD symptoms were measured with a 14-item checklist covering DSM-III-R criteria (parental rating) at age 8 to 9 years and 13 to 14 years. We used both a dichotomous approach for birth weight (>400 g or 15% weight difference) and ADHD (eight or more symptoms) and continuous measures to investigate between- and within-twin pair effects. Our results showed that low birth weight was a risk factor for symptoms of ADHD and the associations did not diminish when we controlled for genetic influence. The lighter twin in birth weight-discordant pairs had on average 13% higher ADHD symptom score at age 8 to 9 years (p = .006) and 12% higher ADHD score at age 13 to 14 years (p = .018) compared with the heavier twin. The genetic correlations suggest modest or no genetic overlap between birth weight and ADHD. The hypothesis that low birth weight is associated with the development of ADHD symptoms was supported in this prospective twin study. Fetal growth restriction seems to represent a modest but fairly consistent environmental influence on the development of ADHD symptoms.

Placental sharing, birthweight discordance and vascular anastomoses in monochorionic diamniotic twin placentas

ObjectiveTo examine the relationship between the discordance in placental territory (PT), birthweight (BW), and vascular anastomoses in placentas from a prospective series of monochorionic diamniotic (MCDA) twins included in the 1st trimester.Study designCord vessels were injected with dyed barium sulphate. Rx angiograms and digital photographs of the chorionic surface were taken. BW discordance was defined as BW heavier/BW lighter twin. PT discordance was determined on Rx angiogram as the ratio of venous surface areas of the larger and smaller placental part. On the digital photograph, minimal diameters (mm) of arterio-arterial (AAs) and of each vein of an arterio-venous (AV) anastomosis were measured. An estimate of net AV transfusion was calculated as the difference of total diameters of AVs draining in either direction.Results76 placentas were analysed. BW discordance increased with PT discordance (P<0.0001). AA diameter (P<0.01) and net AV transfusion (P<0.001) towards the larger placental part increased with PT discordance. For a given PT discordance, BW discordance decreased with increasing AA diameter (P<0.01) and net AV transfusion towards the larger placental part (P<0.05).ConclusionUnequally shared placentas have larger AAs and a larger estimated net AV transfusion towards the larger placental part, as compared to equally shared placentas, which decreases BW discordance for a given PT discordance. Supported by European Commission-Eurotwin2twin - QLG1-CT-2002-01632. ObjectiveTo examine the relationship between the discordance in placental territory (PT), birthweight (BW), and vascular anastomoses in placentas from a prospective series of monochorionic diamniotic (MCDA) twins included in the 1st trimester. To examine the relationship between the discordance in placental territory (PT), birthweight (BW), and vascular anastomoses in placentas from a prospective series of monochorionic diamniotic (MCDA) twins included in the 1st trimester. Study designCord vessels were injected with dyed barium sulphate. Rx angiograms and digital photographs of the chorionic surface were taken. BW discordance was defined as BW heavier/BW lighter twin. PT discordance was determined on Rx angiogram as the ratio of venous surface areas of the larger and smaller placental part. On the digital photograph, minimal diameters (mm) of arterio-arterial (AAs) and of each vein of an arterio-venous (AV) anastomosis were measured. An estimate of net AV transfusion was calculated as the difference of total diameters of AVs draining in either direction. Cord vessels were injected with dyed barium sulphate. Rx angiograms and digital photographs of the chorionic surface were taken. BW discordance was defined as BW heavier/BW lighter twin. PT discordance was determined on Rx angiogram as the ratio of venous surface areas of the larger and smaller placental part. On the digital photograph, minimal diameters (mm) of arterio-arterial (AAs) and of each vein of an arterio-venous (AV) anastomosis were measured. An estimate of net AV transfusion was calculated as the difference of total diameters of AVs draining in either direction. Results76 placentas were analysed. BW discordance increased with PT discordance (P<0.0001). AA diameter (P<0.01) and net AV transfusion (P<0.001) towards the larger placental part increased with PT discordance. For a given PT discordance, BW discordance decreased with increasing AA diameter (P<0.01) and net AV transfusion towards the larger placental part (P<0.05). 76 placentas were analysed. BW discordance increased with PT discordance (P<0.0001). AA diameter (P<0.01) and net AV transfusion (P<0.001) towards the larger placental part increased with PT discordance. For a given PT discordance, BW discordance decreased with increasing AA diameter (P<0.01) and net AV transfusion towards the larger placental part (P<0.05). ConclusionUnequally shared placentas have larger AAs and a larger estimated net AV transfusion towards the larger placental part, as compared to equally shared placentas, which decreases BW discordance for a given PT discordance. Supported by European Commission-Eurotwin2twin - QLG1-CT-2002-01632. Unequally shared placentas have larger AAs and a larger estimated net AV transfusion towards the larger placental part, as compared to equally shared placentas, which decreases BW discordance for a given PT discordance. Supported by European Commission-Eurotwin2twin - QLG1-CT-2002-01632.

Low-cost, dual-mode enhanced vision sensor prototype

As a member of the Southeast SATSLab Consortium and participant in the NASA Small Aircraft Transportation System (SATS) program, the Rockwell Collins Advanced Technology Center has developed a flyable prototype of a low-cost, dual-mode enhanced vision sensor (EVS). The prototype has been successfully flown on Embry-Riddle Aeronautical University's experimental Cessna 310 light twin aircraft. The dual-mode system incorporates an uncooled long wave infrared sensor and a low-light level visible light imager using a common aperture. The system includes a dichroic beamsplitter that provides the same coaxial field of view to both sensors. This paper describes the design, fabrication, sensor performance, and flight test results of the enhanced vision sensor prototype

Discordant twin growth in utero and differences in blood pressure and endothelial function at 8 years of age

Low birth weight is associated with increased prevalence of hypertension and cardiovascular disease in adults. The aim of this study was to evaluate genetic and intrauterine environmental contributions to blood pressure (BP) and vascular functions in twins with discordant growth in utero. We studied 31 twin pairs (21 monozygous and nine dizygous), mean age 8 years) with large within-pair differences in birth weight. Among the monozygous pairs, nine had suffered from twin-to-twin-transfusion syndrome (TTTS). Apart from BP, we determined diameters and elasticity of the carotid artery and abdominal aorta with ultrasonography, and endothelial function in skin vessels with a laser Doppler technique, before and after transdermal delivery of acetylcholine and nitroglycerin. Eight of 62 twin subjects had a systolic BP above the 90th percentile in a North-American reference population. Among these, seven/eight were monozygous with a history of poor fetal growth and/or TTTS. In monozygous twin pairs without TTTS, systolic BP and pulse pressure were higher and vascular endothelial function was impaired in the lower birth weight twin. In the TTTS group, the lighter twin had a narrower carotid artery but there was no within-pair difference in arterial elasticity. Pre-eclampsia during the index pregnancy enhanced within-pair differences in BP but abolished within-pair differences in endothelial function. Severe fetal growth retardation contributes to higher BP, arterial narrowing and endothelial dysfunction in childhood. Pre-eclampsia may act both as an effect modifier and confounder of these associations.

The influence of maternal BMI and age in twin pregnancies on insulin resistance in the offspring.

There is strong evidence that low birth weight is associated with glucose intolerance and diabetes in adults. We have carried out a twin study to distinguish among maternal influences, which affect both twins; fetoplacental influences, which are unique to each twin; and the genetic factors that may underlie this association. We identified a sample of 423 twin pairs (250 monozygotic and 173 dizygotic) from the East Flanders Prospective Twin Survey who were born between 1964 and 1982. Data collected in this study included the mother's body composition and weight gain during pregnancy, the twins' birth weights, and gestational age. The twins (aged 18-34 years) attended a research center for measurement of height, weight, and waist-to-hip ratio as well as fasting glucose, proinsulin, and insulin concentrations. Among twin pairs discordant for birth weight, we found little evidence that the lighter twin had abnormal glucose-insulin metabolism in adult life. However, both a low prepregnancy maternal BMI and older maternal age at delivery were associated with hyperinsulinemia and evidence of insulin resistance in the offspring. Fasting insulin increased by 1.3% (95% CI 0.1-2.6%) per unit fall in maternal BMI and by 1.1% (0.02-2.0%) per year increase in maternal age. These associations were independent of the twins' BMI and waist-to-hip ratio and their zygosity. These novel findings suggest that in twin pregnancies, maternal factors are more important than fetoplacental factors in determining glucose-insulin metabolism in the offspring.

Birth weight and body composition in young women: a prospective twin study

The intrauterine environment may be critical for the development of obesity. Alternatively, the same genetic factors may influence both birth weight and adult body composition. We evaluated the association between birth weight and adult body composition in female twins, which allowed us to control for maternal and genetic influences. Of 447 twin pairs randomly selected from the East Flanders Prospective Twin Survey, 238 pairs, aged 18-34 y, participated. Adult body mass, height, and lean body mass were measured, and the body mass index (BMI), waist-to-hip ratio, and sum of skinfold thicknesses were calculated. The twins were considered as individuals and pairs. When the twins were considered as individuals, twins who were heavier at birth were taller (3.3 cm/kg greater birth weight) and slightly heavier (1.13 kg/kg greater birth weight) as adults than were lighter twins. They also had more lean body mass and less subcutaneous and abdominal fat at birth. Pairwise comparison showed that for every level of intrapair birth weight difference (> or = 5%, > or = 10%, and > or = 15%), the twin who was heavier at birth was taller in adult life (0.8, 1.2, and 2.0 cm, respectively). When the intrapair birth weight difference exceeded 15%, the heavier twin was also heavier (3.1 +/- 6.08 kg) as an adult than her much lighter sister. Birth weight accounts for some of the differences in adult body composition between twins.