The electromagnetic form factors of the proton and neutron encode information on the spatial structure of their charge and magnetization distributions. While measurements of the proton are relatively straightforward, the lack of a free neutron target makes measurements of the neutron's electromagnetic structure more challenging and more sensitive to experimental or model-dependent uncertainties. Various experiments have attempted to extract the neutron form factors from scattering from the neutron in deuterium, with different techniques providing different, and sometimes large, systematic uncertainties.
View Article and Find Full Text PDFWhen protons and neutrons (nucleons) are bound into atomic nuclei, they are close enough to feel significant attraction, or repulsion, from the strong, short-distance part of the nucleon-nucleon interaction. These strong interactions lead to hard collisions between nucleons, generating pairs of highly energetic nucleons referred to as short-range correlations (SRCs). SRCs are an important but relatively poorly understood part of nuclear structure, and mapping out the strength and the isospin structure (neutron-proton (np) versus proton-proton (pp) pairs) of these virtual excitations is thus critical input for modelling a range of nuclear, particle and astrophysics measurements.
View Article and Find Full Text PDFJ Clin Psychol Med Settings
September 2022
Pediatric pain conditions are not uncommon and may lead to functional disability. The purpose of this study is to examine indirect effects of pain catastrophizing on functional disability through anxiety, depression, and pain in youth with chronic pain. Participants included 197 youth (144 females, M = 14.
View Article and Find Full Text PDFMultiple lines of evidence suggest that a deficiency of Fragile X Mental Retardation Protein (FMRP) mediates dysfunction of the metabotropic glutamate receptor subtype 5 (mGluR5) in the pathogenesis of fragile X syndrome (FXS), the most commonly known single-gene cause of inherited intellectual disability (ID) and autism spectrum disorder (ASD). Nevertheless, animal and human studies regarding the link between FMRP and mGluR5 expression provide inconsistent or conflicting findings about the nature of those relationships. Since multiple clinical trials of glutamatergic agents in humans with FXS did not demonstrate the amelioration of the behavioral phenotype observed in animal models of FXS, we sought measure if mGluR5 expression is increased in men with FXS to form the basis for improved clinical trials.
View Article and Find Full Text PDFSickle cell disease (SCD) is an inherited hemoglobinopathy with an increased risk of neurological complications. Due to anemia and other factors related to the underlying hemoglobinopathy, cerebral blood flow (CBF) increases as compensation; however, the nature of alterations in oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO) in SCD remains controversial, largely attributed to the different calibration models. In addition, limited studies have been done to investigate oxygen metabolism in pediatric patients.
View Article and Find Full Text PDFGlutamatergic receptor expression is mostly unknown in adults with fragile X syndrome (FXS). Favorable behavioral effects of negative allosteric modulators (NAMs) of the metabotropic glutamate receptor subtype 5 (mGluR) in knockout (KO) mouse models have not been confirmed in humans with FXS. Measurement of cerebral mGluR expression in humans with FXS exposed to NAMs might help in that effort.
View Article and Find Full Text PDFAdolescents with diabetes have a higher prevalence of depression compared with their peers. The American Diabetes Association recommends routine mental health screening for youth with diabetes. This screening is often conducted through accessible and free depression screeners, such as the nine-item Patient Health Questionnaire (PHQ-9).
View Article and Find Full Text PDFWe present extractions of the nucleon nonsinglet moments utilizing new precision data on the deuteron F_{2} structure function at large Bjorken-x determined via the Rosenbluth separation technique at Jefferson Lab Experimental Hall C. These new data are combined with a complementary set of data on the proton previously measured in Hall C at similar kinematics and world datasets on the proton and deuteron at lower x measured at SLAC and CERN. The new Jefferson Lab data provide coverage of the upper third of the x range, crucial for precision determination of the higher moments.
View Article and Find Full Text PDFThe Spin Asymmetries of the Nucleon Experiment measured two double spin asymmetries using a polarized proton target and polarized electron beam at two beam energies, 4.7 and 5.9 GeV.
View Article and Find Full Text PDFObjectives: Attention-deficit/hyperactivity disorder (ADHD) is a common neurological disorder with symptom onset early in childhood. Growing evidence suggests anomalous brain development across multiple brain regions is evident in school-aged children; however, few studies have examined whether such differences are notable in the preschool years when symptom onset typically occurs.
Methods: High resolution anatomical (MPRAGE) images and cognitive and behavioral measures were analyzed in a total of 90 medication-naïve preschoolers, ages 4-5 years (52 with ADHD, 38 controls; 64.
We measured the g_{1} spin structure function of the deuteron at low Q^{2}, where QCD can be approximated with chiral perturbation theory (χPT). The data cover the resonance region, up to an invariant mass of W≈1.9 GeV.
View Article and Find Full Text PDFWide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θ_{cm}^{p}=70°.
View Article and Find Full Text PDFBackground: Adolescents are prone to sleep problems that have unique developmental aspects and contribute to physical, emotional, and behavioural problems.
Aims: This study evaluated an individualized, multicomponent intervention that considered developmental factors, and promoted age-appropriate autonomy in three adolescent females with disrupted sleep.
Method: Adolescents recorded sleep data on daily logs.
We studied simultaneously the (4)He(e,e'p), (4)He(e,e'pp), and (4)He(e,e'pn) reactions at Q(2)=2(GeV/c)(2) and x(B)>1, for an (e,e'p) missing-momentum range of 400 to 830 MeV/c. The knocked-out proton was detected in coincidence with a proton or neutron recoiling almost back to back to the missing momentum, leaving the residual A=2 system at low excitation energy. These data were used to identify two-nucleon short-range correlated pairs and to deduce their isospin structure as a function of missing momentum, in a region where the nucleon-nucleon (NN) force is expected to change from predominantly tensor to repulsive.
View Article and Find Full Text PDFElectroencephalograms (EEGs) and polysomnograms (PSGs) are critical and frequently ordered tests in the care of children with neurodevelopmental disabilities (NDD). Performing studies with this population can be very intimidating, given that the referral reasons and seizure types can be unique, and children with NDD may have any combination of behavioral or sensory challenges that can make it difficult to successfully complete a study. This article presents a variety of strategies that can be used to overcome these challenges through good preparation, patience, caregiver involvement, effective behavioral management techniques, and education about the medical aspects of EEG/ PSG in NDD.
View Article and Find Full Text PDFWe report the first measurement of the parity-violating asymmetry A(PV) in the elastic scattering of polarized electrons from 208Pb. A(PV) is sensitive to the radius of the neutron distribution (R(n)). The result A(PV)=0.
View Article and Find Full Text PDFWe present new measurements of electron scattering from high-momentum nucleons in nuclei. These data allow an improved determination of the strength of two-nucleon correlations for several nuclei, including light nuclei where clustering effects can, for the first time, be examined. The data also include the kinematic region where three-nucleon correlations are expected to dominate.
View Article and Find Full Text PDFThe (2)H(e,e'p)n cross section at a momentum transfer of 3.5 (GeV/c)(2) was measured over a kinematical range that made it possible to study this reaction for a set of fixed missing momenta as a function of the neutron recoil angle θ(nq) and to extract missing momentum distributions for fixed values of θ(nq) up to 0.55 GeV/c.
View Article and Find Full Text PDFAttention-deficit/hyperactivity disorder (ADHD) is a developmental disorder that, by current definition, has onset prior to age 7 years. MRI studies have provided some insight into brain differences associated with ADHD, but thus far have almost exclusively focused on children ages 7 years and older. To better understand the neurobiological development of ADHD, cortical and subcortical brain development should be systematically examined in younger children presenting with symptoms of the disorder.
View Article and Find Full Text PDFA behavior therapy approach for obtaining cooperation during needle sticks was provided to 8 pediatric patients with intellectual and developmental disabilities. Therapy was provided during mock needle sticks. Hand lotion was applied to simulate topical anesthetic.
View Article and Find Full Text PDFPhys Rev Lett
November 2010
We present new data on electron scattering from a range of nuclei taken in Hall C at Jefferson Lab. For heavy nuclei, we observe a rapid falloff in the cross section for x>1, which is sensitive to short-range contributions to the nuclear wave function, and in deep inelastic scattering corresponds to probing extremely high momentum quarks. This result agrees with higher energy muon scattering measurements, but is in sharp contrast to neutrino scattering measurements which suggested a dramatic enhancement in the distribution of the "superfast" quarks probed at x>1.
View Article and Find Full Text PDFWe have extracted QCD matrix elements from our data on doubly polarized inelastic scattering of electrons on nuclei. We find the higher twist matrix element d˜2, which arises strictly from quark-gluon interactions, to be unambiguously nonzero. The data also reveal an isospin dependence of higher twist effects if we assume that the Burkhardt-Cottingham sum rule is valid.
View Article and Find Full Text PDFSmith-Lemli-Opitz syndrome (SLOS) is a genetic syndrome associated with multiple congenital malformations, mental retardation, and autism spectrum behaviors. This clinical protocol was part of a larger study investigating the effects of a cholesterol-lowering medication for SLOS patients. Behavioral therapists were consulted to facilitate participants' cooperation with an overnight electroencephalogram (EEG).
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