Hereditary Contributions Research Articles

Higher-order tail contributions to the energy and angular momentum fluxes in a two-body scattering process

The need for more and more accurate gravitational wave templates requires taking into account all possible contributions to the emission of gravitational radiation from a binary system. Therefore, working within a multipolar-post-Minkowskian framework to describe the gravitational wave field in terms of the source multipole moments, the dominant instantaneous effects should be supplemented by hereditary contributions arising from nonlinear interactions between the multipoles. The latter effects are referred to as tails being described in terms of integrals depending on the past history of the source. We compute higher-order tail (i.e., tail-of-tail and tail-squared) contributions to both energy and angular momentum fluxes and their averaged values along hyperboliclike orbits at the leading post-Newtonian approximation, using harmonic coordinates and working in the Fourier domain. Due to the increasing level of accuracy recently achieved in the determination of the scattering angle in a two-body system by several complementary approaches, the knowledge of these terms will provide useful information to compare results from different formalisms.

Dissipative and generative fractional electric elements in modeling $${\varvec{RC}}$$ and $${\varvec{RL}}$$ circuits

Two types of constitutive equations consisting of instantaneous and power type hereditary contributions are proposed in order to model generalized capacitor (inductor). The first one, that expresses charge (magnetic flux) in terms of voltage (current) memory, proved to describe a dissipative electric element, while the second one, that expresses voltage (current) in terms of charge (magnetic flux) memory, proved to describe a generative electric element. These constitutive models are used in transient and steady state regime analysis of the series RC and RL circuits subject to electromotive force, as well as in the study of circuits’ frequency characteristics including their asymptotic behavior.

Genome-Wide Association Study (GWAS) of High-Risk Minimal Residual Disease and Relapse in B-Cell Acute Lymphoblastic Leukemia on Trial AIEOP-BFM ALL 2000

▪A significant proportion of patients with pediatric acute lymphoblastic leukemia (ALL) still suffers from relapse and therapy-related toxicities. Thus, the focus of further improvement of therapy for them is not only cure, but minimizing both short-term and long-term therapy-associated toxicity. This can be achieved by better personalized adjustment of therapy to the risk of relapse. Continuing research has identified numerous features with prognostic potential, including clinical and genetic variables as well as early response to chemotherapy being associated with treatment outcome. While most research activities on genetic prognostic factors have focused on somatic features, relatively little is known on hereditary contributions to treatment response and outcome in pediatric ALL. Therefore, we conducted a genome-wide association study (GWAS) of high-risk minimal residual disease (MRD) and relapse in B cell precursor (BCP) ALL patients treated on trial AIEOP-BFM ALL 2000.On this trial, patients were stratified into three risk groups, mainly by MRD analyses. MRD standard-risk (MRD-SR) patients were MRD-negative on treatment days 33 and 78, MRD high-risk (MRD-HR) patients had residual disease of ≥5x10-4 on treatment day 78. All the remaining MRD results were considered MRD intermediate-risk (MRD-IR). Besides MRD, established high-risk parameters were also retained for stratification: prednisone poor-response, induction failure, positivity for t(4;11)/ MLL-AF4 . Treatment used standard drugs and, in some of the patients, cranial irradiation and/or hematopoietic stem cell transplantation. DNA isolated from remission samples was genotyped using Illumina Human1M-Duo BeadChips containing 1.048.711 single SNV markers. For GWAS analyses gPLINK v2.050, PLINK v.1.09 and RStatistics v3.3.1 were used. The analysis on MRD was conducted in 69 MRD-HR patients (cases) and in 1034 patients of the MRD-SR and MRD-IR groups (controls). The analysis on relapse employed 145 relapsed (cases) and 1007 non-relapsed patients (controls). After quality control assessment, the final analyses included 749.262 SNPs among 62 MRD-HR patients compared to 927 controls and 129 relapsed patients compared to 925 controls.In the analysis on MRD-HR five SNVs reached genome-wide significance at P ≤5×10−8. An intronic SNV (rs1570765) in STARD13 demonstrated the strongest association (P =1.73x10-10; odds ratio, OR=5.06). Two additional SNVs with P ≤5×10−8 in STARD13 were in linkage disequilibrium with rs1570765. The two remaining SNVs with P ≤5×10−8 were located in FEZ2 and NRIP1. Five additional SNVs demonstrated significant levels of ≤1×10−6 and were associatedwith the following genes: STARD13 , VIT and FICD . STARD13 is located on chromosome 13, belongs to the family of RhoGap proteins and is frequently lost in hepatocellular and breast carcinomas. Its RhoGAP domain activates members of the Ras superfamily which leads to a suppression of cell growth and differentiation (Lin et al. Oncogene 2010). In the GWAS approach on relapse three SNVs reached significant levels of ≤1×10−6 and were associatedwith the genes ASB3 (rs1549749, P =3.51x10-7; rs12465316, P =4.26x10-7) on chromosome 2 and NDN (rs9972595, P =1.04x10-6) on chromosome 15. Twenty additional SNVs demonstrated significance levels of ≤1×10−5. ASB3 codes for a member of the ankyrin repeat and SOCS box-containing (ASB) family of proteins containing ankyrin repeat sequence and a SOCS box domain. The latter serves to couple suppressor of cytokine signalling (SOCS) proteins and their binding partners with the elongin B and C complex, possibly targeting them for degradation. NDN , a p53 target gene, codes for Necdin which was previously shown to regulate the quiescence and response to genotoxic stress of hematopoietic stem/progenitor cells (Asai et al., Blood 2012). Further replication results, an analysis of additive effects and multivariate analyses will be presented.In conclusion, our results demonstrate that germline genetic variation is associated with high levels of MRD after induction/consolidation treatment for ALL and relapse on an AIEOP-BFM ALL protocol. In line with previous studies (Yang et al., JAMA 2009), our data suggest that genome-wide approaches may be useful to identify novel and clinically relevant SNVs for further refinement of risk-adapted treatment strategies in pediatric ALL. DisclosuresSchrappe:JAZZ Pharma: Consultancy, Research Funding; SigmaTau: Consultancy, Research Funding; Medac: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Baxalta: Consultancy, Research Funding.

Cytogenomic aberrations in isolated multicystic dysplastic kidney in children.

Background:Multicystic dysplastic kidney (MCDK) is a common form of congenital kidney anomaly. The cause of MCDK is unknown. We investigated whether MCDK in children is linked to cytogenomic aberrations.Methods:We conducted Array Comparative Genomic Hybridization (aCGH) in 10 unrelated children with MCDK. The pattern of inheritance was determined by real-time PCR in patients and their biological parents.Results:Pathogenic aberrations were detected in three patients: a deletion at 7p14.3 with a size of 2.07 Mb housing 12 genes, including BBS9 and BMPER; a duplication at 16p13.11p12.3 with a size of 3.28 Mb that included more than 20 genes; and monosomy X for a female patient. The deletion at 7p14.3 was inherited from patient’s father, while the duplication at 16p13.11p12.3 was derived from patient’s mother.Conclusions:Up to 30% of patients with MCDK possess cytogenomic aberrations. BBS9 and BMPER variants have been reported to result in cystic kidney dysplasia, suggesting possible pathogenic function for the deletion at 7p14.3 in children with MCDK. The duplication at 16p13.11p12.3 was not reported previously to associate with MCDK. Both variations were inherited from parents, indicating hereditary contributions in MCDK. Thus, aCGH is an informative tool to unravel pathogenic mechanisms of MCDK.

Fractional [formula omitted] circuit in transient and steady state regimes

Assuming accumulated charge being dependent on capacitor voltage memory as well as by expressing magnetic flux in inductor in terms of current memory, generalized capacitor and inductor are constitutively modeled by the sum of terms containing instantaneous and power type hereditary contributions. Constitutive models are further used in analyzing transient and steady state responses of series RLC circuit subject to electromotive force. Depending on model parameters, the character of transfer function changes the behavior of fractional RLC circuit’s impulse response in transient regime from aperiodic, over critically aperiodic, to damped oscillatory. Transition from transient to steady state regime is also analyzed, so as its predominant type depending on element’s fractional order.

Determination of new coefficients in the angular momentum and energy fluxes at infinity to 9PN order for eccentric Schwarzschild extreme-mass-ratio inspirals using mode-by-mode fitting

We present an extension of work in an earlier paper showing high precision comparisons between black hole perturbation theory and post-Newtonian (PN) theory in their region of overlapping validity for bound, eccentric-orbit, Schwarzschild extreme-mass-ratio inspirals. As before we apply a numerical fitting scheme to extract eccentricity coefficients in the PN expansion of the gravitational wave fluxes, which are then converted to exact analytic form using an integer-relation algorithm. In this work, however, we fit to individual $lmn$ modes to exploit simplifying factorizations that lie therein. Since the previous paper focused solely on the energy flux, here we concentrate initially on analyzing the angular momentum flux to infinity. A first step involves finding convenient forms for hereditary contributions to the flux at low-PN order, analogous to similar terms worked out previously for the energy flux. We then apply the upgraded techniques to find new PN terms through 9PN order and (at many PN orders) to $e^{30}$ in the power series in eccentricity. With the new approach applied to angular momentum fluxes, we return to the energy fluxes at infinity to extend those previous results. Like before, the underlying method uses a \textsc{Mathematica} code based on use of the Mano-Suzuki-Takasugi (MST) function expansion formalism to represent gravitational perturbations and spectral source integration (SSI) to find numerical results at arbitrarily high precision.

Authenticating the Presence of a Relativistic Massive Black Hole Binary in OJ 287 Using Its General Relativity Centenary Flare: Improved Orbital Parameters

Abstract Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission of gravitational waves (GWs). We show that observations associated with the binary black hole (BBH) central engine of blazar OJ 287 demand the inclusion of gravitational radiation reaction effects beyond the quadrupolar order. It turns out that even the effects of certain hereditary contributions to GW emission are required to predict impact flare timings of OJ 287. We develop an approach that incorporates this effect into the BBH model for OJ 287. This allows us to demonstrate an excellent agreement between the observed impact flare timings and those predicted from ten orbital cycles of the BBH central engine model. The deduced rate of orbital period decay is nine orders of magnitude higher than the observed rate in PSR 1913+16, demonstrating again the relativistic nature of OJ 287's central engine. Finally, we argue that precise timing of the predicted 2019 impact flare should allow a test of the celebrated black hole “no-hair theorem” at the 10% level.

Foundations of an effective-one-body model for coalescing binaries on eccentric orbits

We develop the foundations of an effective-one-body (EOB) model for eccentric binary coalescences that includes the conservative dynamics, radiation reaction, and gravitational waveform modes from the inspiral and the merger-ringdown signals. We use the same approach as is commonly employed in black-hole perturbation theory by introducing a relativistic parameterization of the dynamics that is defined by the orbital geometry and consists of a set of phase variables and quantities that evolve only due to gravitational radiation reaction. Specializing to nonspinning binaries, we derive the EOB evolution equations and compute the binary's radiative multipole moments that determine the gravitational waves through a decomposition into the fundamental frequencies of the motion. The major differences between our treatment and the quasi-Keplerian approach often used in post-Newtonian (PN) calculations are that the orbital parameters describe strong-field dynamics, and that expressing the multipole moments in terms of the frequencies simplifies the calculations and also results in an unambiguous orbit-averaging operation. While our description of the conservative dynamics is fully relativistic, we limit explicit derivations in the radiative sector to 1.5PN order for simplicity. This already enables us to establish methods for computing both instantaneous and hereditary contributions to the gravitational radiation in EOB coordinates that have straightforward extensions to higher PN order. The weak-field, small eccentricity limit of our results for the orbit-averaged fluxes of energy and angular momentum agrees with known PN results when expressed in terms of gauge-invariant quantities. We further address considerations for the numerical implementation of the model and the completion of the waveforms to include the merger and ringdown signals, and provide illustrative results.

Endo-lysosomal and autophagic dysfunction: a driving factor in Alzheimer's disease?

Alzheimer's disease (AD) is the most common cause of dementia, and its prevalence will increase significantly in the coming decades. Although important progress has been made, fundamental pathogenic mechanisms as well as most hereditary contributions to the sporadic form of the disease remain unknown. In this review, we examine the now substantial links between AD pathogenesis and lysosomal biology. The lysosome hydrolyses and processes cargo delivered by multiple pathways, including endocytosis and autophagy. The endo-lysosomal and autophagic networks are central to clearance of cellular macromolecules, which is important given there is a deficit in clearance of amyloid-β in AD. Numerous studies show prominent lysosomal dysfunction in AD, including perturbed trafficking of lysosomal enzymes and accumulation of the same substrates that accumulate in lysosomal storage disorders. Examination of the brain in lysosomal storage disorders shows the accumulation of amyloid precursor protein metabolites, which further links lysosomal dysfunction with AD. This and other evidence leads us to hypothesise that genetic variation in lysosomal genes modifies the disease course of sporadic AD.

An Exploratory Study of Hope and Its Process Using Focus Groups and Phenomenological Analysis

Snyder (2000) describes the beginning of hope with the story of Pandora, beautiful maiden who was sent to earth by the Gods to fulfill revenge from Prometheus as he had stolen fire. Sent with beautiful jar, Pandora could not wait to open it though being instructed not to do so. She was horrified to see all the evils being out of the jar and she quickly shut it close leaving hope behind in it. Snyder developed the hope theory which has received the most attention since the 1990s.Snyder defines hope as: is the sum of perceived capabilities to produce routes to desired goals, along with the perceived motivation to use those routes. One form of the definition was, a positive motivational state that is based on an interactively derived sense of successful agency (goal-directed energy) and pathways (planning to meet goals) (Snyder, Irving & Anderson, 1991). A second definition described it as a cognitive set that is based on reciprocally-derived sense of successful agency (goal-directed determination) and pathways (planning to meet goals) (Snyder, Harris, Anderson, Holleran, Irving, Sigmon, Yoshinobu, Gibb, Langelle, & Harney, 1991).Goals work as an anchor in the process of hoping and have been seen as cognitive components. These goals could be short term or long term and not necessarily as visual images or verbal descriptions. When one is sure of achieving the goals, one need not hope for it and when one is certain of not being able to achieve them, then also one does not hope. It is in the intermediate probability of achieving goals that hope flourishes the most. The routes which individuals use to reach their goals are termed as Pathways thoughts. In simple words it means to think as to how can one reach from Ato B. Agency thoughts are understood as mental force which motivates individuals to use the located routes to reach out to their goals. It is this agency thinking which provides us with 'push' to move ahead whenever we are faced with impediments to reach our goals.Snyder (1994) also proposes that hope has no hereditary contributions and it is rather an entirely learned cognitive set about goal-directed thinking. The teachings of pathways and agentic thinking is seen as an inherent part of parenting which helps the child to bring in the components of hopeful thinking in place by the age of two years. Pathways thinking is the basic cause and effect learning that the child acquires from interactions with caregivers and this is achieved before age one year with agency thinking developing around age one year. Snyder (1994, 2000) has stated that strong attachment to caregivers is crucial for imparting hope.Hope has received little attention due to its superficial analysis. Philip Pettit (2004) in his conceptual paper 'Hope and its place in mind' argues that the term 'hope' should be utilized in more specific way. Such usage would give hope characteristic identity of its own. He believes that hope is very distinctive state of mind and has rational andubiquitous place in human life. A prerequisite to hope is to believe that hope is not forlorn. One must believe that hope is true and will be realized.Pettit also agrees that hope requires elements of beliefs and desires but with this it also requires something else and that something else gives hope its characteristic identity. Hope is rational as it helps us to bring ourselves out of the panics and depressions and gives us control and direction. Without hope, we would collapse in despair and uncertainty. Hope is also seen as cognitive counterpart of planning wherein an action plan is seen as way of handling the rough and tumble of desire which keeps anything else which is inconsistent at rest. Such planning gives kind of coordination in an uncertain and uncompanionable world.In another conceptual paper 'An Anatomy of Hope' by Roberts Mills (1979), finds common roots between the words 'hope' and 'hopelessness'. …

Duplicated copy of CHRNA7 increases risk and worsens prognosis of COPD and lung cancer.

Recent genome-wide association studies implicated that the nicotinic acetylcholine receptors (nAChRs) are common susceptible genes of two contextual diseases: chronic obstructive pulmonary disease (COPD) and lung cancer. We aimed to test whether the copy number variations (CNVs) in nAChRs have hereditary contributions to development of the two diseases. In two, two-stage, case-control studies of southern and eastern Chinese, a common CNV-3956 that duplicates the cholinergic receptor, nicotinic, α7 (CHRNA7) gene was genotyped in a total of 7880 subjects and its biological phenotype was assessed. The ≥4-copy of CNV-3956 increased COPD risk (≥4-copy vs 2/3-copy: OR=1.44, 95% CI=1.23-1.68) and caused poor lung function, and it similarly augmented risk (OR=1.49, 95% CI=1.29-1.73) and worsened prognosis (hazard ratio (HR)=1.25, 95% CI=1.07-1.45) of lung cancer. The ≥4-copy was estimated to account for 1.56% of COPD heritability and 1.87% of lung cancer heritability, respectively. Phenotypic analysis further showed that the ≥4-copy of CNV-3956 improved CHRNA7 expression in vivo and increased the carriers' smoking amount. The CNV-3956 of CHRNA7 contributed to increased risks and poor prognoses of both COPD and lung cancer, and this may be a genetic biomarker of the two diseases.

Beyond the Brain: The Role of Bullying in Adolescent Substance Abuse

Among the most important contributions to the understanding and treatment of addiction is the abandonment of the notion that substance abuse is a moral failing, a lifestyle choice, or character flaw, but instead has biological, hereditary contributions that predict its occurrence and course. Defining addiction as a chronic, relapsing brain disease characterized by compulsive drug seeking and use, despite negative consequences, has transformed the medical and psychological study of addiction since the 1930’s [1]. Indeed, scientists estimate that genetic factors account for approximately 40% to 60% of an individual’s vulnerability to addiction, including the role of the environment on gene expression and function [1]. Specifically, since abnormalities in the reward system of the brain (e.g. liking, wanting, and learning) are believed to play a role in numerous psychiatric disorders, including substance abuse, study of the functional neuroanatomy of reward has been seen as critically important in neuropsychiatry [2]. From a neurobiological perspective, addiction is a disorder of brain reward mechanisms (e.g. the dopamine pathway, among other neurotransmitters) that are critical for survival [2].

Toward a Genetic Understanding of Glaucoma-Breakthroughs and Challenges from Studies of Exfoliation Glaucoma.

Glaucoma is a complex group of diseases causing progressive degeneration of the optic nerve. Despite strong evidence of hereditary contributions to glaucoma, relatively few genetic mutations associated with glaucoma risk have thus far been identified. Glaucoma likely represents a complex genetic trait influenced by multiple loci and many confounding factors, increasing the challenge in identifying glaucoma’s hereditary basis. In this article, a brief history of the search for glaucoma-causing mutations is presented, highlighting recent breakthroughs that have identified lysyl oxidase-like 1 (LOXL1) as a major genetic risk factor contributing to exfoliative glaucoma. In considering challenges that remain ahead, our central tenet is that the search for glaucoma’s genetic elements will continue to require experimental ingenuity and synergistic approaches involving animal models that render the complexity of glaucoma more tractable.

Head-on infall of two compact objects: Third post-Newtonian energy flux

Head-on infall of two compact objects with arbitrary mass ratio is investigated using the multipolar post-Minkowskian approximation method. At the third post-Newtonian order the energy flux, in addition to the instantaneous contributions, also includes hereditary contributions consisting of the gravitational-wave tails, tails-of-tails, and the tail-squared terms. The results are given both for infall from infinity and also for infall from a finite distance. These analytical expressions should be useful for the comparison with the high accuracy numerical relativity results within the limit in which post-Newtonian approximations are valid.

Osteochondral lesions of the talus

Osteochondral lesions of the talus are becoming common problems in orthopaedics, with increasingly significant short-term and long-term morbidity, for which early diagnosis is critical. Trauma is the most common cause; however, the role of ischemic necrosis, hereditary contributions and hormonal factors are still unknown. Technological advancements in CT, MRI and arthroscopy have allowed us to better diagnose and manage this injury. Nonoperative treatment is limited to small, stable lesions (Berndt and Harty stage I-II). Larger lesions (stage III-IV) can be treated effectively by marrow stimulating techniques such as subchondral drilling, especially for older patients. In younger patients with larger lesions, osteochondral autograft procedures (mosaicplasty and osteochondral autograft bone transfer system) and autologous chondrocyte implantation are available and have promising results.

Tail effects in the third post-Newtonian gravitational wave energy flux of compact binaries in quasi-elliptical orbits

The far-zone flux of energy contains hereditary (tail) contr ibutions that depend on the entire past history of the source. Using the multipolar post-Minkowskian wave generation formalism, we propose and implement a semi-analytical method in the frequency domain to compute these contributions from the inspiral phase of a binary system of compact objects moving in quasi-elliptical orbits up to third post-Newtonian (3PN) order. The method explicitly uses the quasi-Keplerian representation of elliptical orbits at 1PN order and exploits the doubly periodic nature of the motion to average the 3PN flu xes over the binary’s orbit. Together with the instantaneous (non-tail) contributions evaluated in a companion paper, it provides crucial inputs for the construction of ready-to-use templates for compact binaries moving on quasi-elliptic orbits, an interesting class of sources for the ground based gravitational wave detectors such as LIGO and Virgo as well as space based detectors like LISA.

Inspiralling compact binaries in quasi-elliptical orbits: The complete third post-Newtonian energy flux

The instantaneous contributions to the third post-Newtonian (3PN) gravitational wave luminosity from the inspiral phase of a binary system of compact objects moving in a quasi-elliptical orbit is computed using the multipolar post-Minkowskian wave generation formalism. The necessary inputs for this calculation include the 3PN accurate mass quadrupole moment for general orbits and the mass octupole and current quadrupole moments at 2PN. Using the recently obtained 3PN quasi-Keplerian representation of elliptical orbits, the flux is averaged over the binary's orbit. Supplementing this by the important hereditary contributions arising from tails, tails of tails, and tails-squared terms calculated in a previous paper, the complete 3PN energy flux is obtained. The final result presented in this paper would be needed for the construction of ready-to-use templates for binaries moving on noncircular orbits, a plausible class of sources not only for the space-based detectors like LISA but also for the ground-based ones.

The longtime behavior of a nonlinear Reissner–Mindlin plate with exponentially decreasing memory kernels

In this paper we investigate the longtime behavior of the mathematical model of a homogeneous viscoelastic plate based on Reissner–Mindlin deformation shear assumptions. According to the approximation procedure due to Lagnese for the Kirchhoff viscoelastic plate, the resulting motion equations for the vertical displacement and the angle deflection of vertical fibers are derived in the framework of the theory of linear viscoelasticity. Assuming that in general both Lame's functions, λ and μ, depend on time, the coupling terms between the equations of displacement and deflection depend on hereditary contributions. We associate to the model a nonlinear semigroup and show the behavior of the energy when time goes on. In particular, assuming that the kernels λ and μ decay exponentially, and not too weakly with respect to the physical properties considered in the model, then the energy decays uniformly with respect to the initial conditions; i.e., we prove the existence of an absorbing set for the semigroup associated to the model.

Terry

Article Abstract Background: Although the relative incidence of violent behavior during sleep (VBS) is presumed to be low, no epidemiologic data exist to evaluate the prevalence of the phenomenon or to begin to understand its precursors or subtypes. This study examined the frequency of violent or injurious behavior during sleep and associated psychiatric risk factors. Method: A representative United Kingdom sample of 2078 men and 2894 women between the ages of 15 to 100 years (representing 79.6% of those contacted) participated in a telephone interview directed by the Sleep-EVAL expert system specially designed for conducting such diagnostic telephone surveys. Results: Two percent (N=106) of respondents reported currently experiencing VBS. The VBS group experienced more night terrors and daytime sleepiness than the non-VBS group. Sleep talking, bruxism, and hypnic jerks were more frequent within the VBS than the other group, as were hypnagogic hallucinations (especially the experience of being attacked), the incidence of smoking, and caffeine and bedtime alcohol intake. The VBS group also reported current features of anxiety and mood disorders significantly more frequently and reported being hospitalized more often during the previous 12 months than the non-VBS group. Subjects with mood or anxiety disorders that co-occurred with other nocturnal symptoms had a higher risk of reporting VBS than all other subjects. Conclusion: We have identified a number of sleep, mental disorder, and other general health factors that characterize those experiencing episodes of VBS. These findings suggest that specific factors, perhaps reflecting an interaction of lifestyle and hereditary contributions, may be responsible for the observed variability in this rare but potentially serious condition.

Heredity and environment in phoneme articulation: hereditary and environmental contributions to articulation proficiency.

Large twin samples and recent applications of multiple regression techniques to behavioral genetics methodology makes possible evaluation of genetic and environmental contributions to the articulation proficiency of individual phonemes. Factor analysis of the articulation scores from 256 MZ and DZ twins and 124 of their non-twin siblings (all children ranged from 2; 11 to 9; 8 years) were conducted to reduce a 50-item articulation test to a more manageable set of five articulation factors. The twins' factor scores were then analyzed using multiple regression procedures to determine the extent to which the individual factors resulted from genetic and/or environmental influences. The /r/ and /[symbol: see text], t[symbol: see text], d[symbol: see text]/ factors were found to have strong genetic components, while the /l, j, w/ factor was found to be strongly influenced by environmental sources of variation.