First Measurement of Hard Exclusive π

The polarized cross-section ratio σ_{LT^{'}}/σ_{0} from hard exclusive π^{-}Δ^{++} electroproduction off an unpolarized hydrogen target has been extracted based on beam-spin asymmetry measurements using a 10.2 GeV/10.6 GeV incident electron beam and the CLAS12 spectrometer at Jefferson Lab. The study, which provides the first observation of this channel in the deep-inelastic regime, focuses on very forward-pion kinematics in the valence regime, and photon virtualities ranging from 1.5 GeV^{2} up to 7 GeV^{2}. The reaction provides a novel access to the d-quark content of the nucleon and to p→Δ^{++} transition generalized parton distributions. A comparison to existing results for hard exclusive π^{+}n and π^{0}p electroproduction is provided, which shows a clear impact of the excitation mechanism, encoded in transition generalized parton distributions, on the asymmetry.

First CLAS12 Measurement of Deeply Virtual Compton Scattering Beam-Spin Asymmetries in the Extended Valence Region.

Deeply virtual Compton scattering (DVCS) allows one to probe generalized parton distributions describing the 3D structure of the nucleon. We report the first measurement of the DVCS beam-spin asymmetry using the CLAS12 spectrometer with a 10.2 and 10.6 GeV electron beam scattering from unpolarized protons. The results greatly extend the Q^{2} and Bjorken-x phase space beyond the existing data in the valence region and provide 1600 new data points measured with unprecedented statistical uncertainty, setting new, tight constraints for future phenomenological studies.

Multidimensional, High Precision Measurements of Beam Single Spin Asymmetries in Semi-inclusive π

High precision measurements of the polarized electron beam-spin asymmetry in semi-inclusive deep inelastic scattering (SIDIS) from the proton have been performed using a 10.6 GeV incident electron beam and the CLAS12 spectrometer at Jefferson Lab. We report here a high precision multidimensional study of single π^{+} SIDIS data over a large kinematic range in Bjorken x, fractional energy, and transverse momentum of the hadron as well as photon virtualities Q^{2} ranging from 1-7 GeV^{2}. In particular, the structure function ratio F_{LU}^{sinϕ}/F_{UU} has been determined, where F_{LU}^{sinϕ} is a twist-3 quantity that can reveal novel aspects of emergent hadron mass and quark-gluon correlations within the nucleon. The data's impact on the evolving understanding of the underlying reaction mechanisms and their kinematic variation is explored using theoretical models for the different contributing transverse momentum dependent parton distribution functions.

Improved Λp Elastic Scattering Cross Sections between 0.9 and 2.0 GeV/c as a Main Ingredient of the Neutron Star Equation of State.

Strange matter is believed to exist in the cores of neutron stars based on simple kinematics. If this is true, then hyperon-nucleon interactions will play a significant part in the neutron star equation of state. Yet, compared to other elastic scattering processes, there is very little data on Λ-N scattering. This experiment utilized the CEBAF Large Acceptance Spectrometer (CLAS) detector to study the Λp→Λp elastic scattering cross section in the incident Λ momentum range 0.9-2.0 GeV/c. These are the first data on this reaction since the 1970s. The new cross sections have significantly better accuracy and precision than the existing world data, and the techniques developed here can also be used in future experiments.

First Measurement of Timelike Compton Scattering.

We present the first measurement of the timelike Compton scattering process, γp→p^{'}γ^{*}(γ^{*}→e^{+}e^{-}), obtained with the CLAS12 detector at Jefferson Lab. The photon beam polarization and the decay lepton angular asymmetries are reported in the range of timelike photon virtualities 2.25

Observation of Beam Spin Asymmetries in the Process ep→e

The observation of beam spin asymmetries in two-pion production in semi-inclusive deep inelastic scattering off an unpolarized proton target is reported. The data presented here were taken in the fall of 2018 with the CLAS12 spectrometer using a 10.6 GeV longitudinally spin-polarized electron beam delivered by CEBAF at JLab. The measured asymmetries provide the first opportunity to extract the parton distribution function e(x), which provides information about the interaction between gluons and quarks, in a collinear framework that offers cleaner access than previous measurements. The asymmetries also constitute the first ever signal sensitive to the helicity-dependent two-pion fragmentation function G_{1}^{⊥}. A clear sign change is observed around the ρ mass that appears in model calculations and is indicative of the dependence of the produced pions on the helicity of the fragmenting quark.

Photoproduction of the f_{2}(1270) Meson Using the CLAS Detector.

The quark structure of the f_{2}(1270) meson has, for many years, been assumed to be a pure quark-antiquark (qq[over ¯]) resonance with quantum numbers J^{PC}=2^{++}. Recently, it was proposed that the f_{2}(1270) is a molecular state made from the attractive interaction of two ρ mesons. Such a state would be expected to decay strongly to final states with charged pions due to the dominant decay ρ→π^{+}π^{-}, whereas decay to two neutral pions would likely be suppressed. Here, we measure for the first time the reaction γp→π^{0}π^{0}p, using the CEBAF Large Acceptance Spectrometer detector at Jefferson Lab for incident beam energies between 3.6 and 5.4 GeV. Differential cross sections, dσ/dt, for f_{2}(1270) photoproduction are extracted with good precision due to low backgrounds and are compared to theoretical calculations.

Beam Spin Asymmetry in Semi-Inclusive Electroproduction of Hadron Pairs.

A first measurement of the longitudinal beam spin asymmetry A_{LU} in the semi-inclusive electroproduction of pairs of charged pions is reported. A_{LU} is a higher-twist observable and offers the cleanest access to the nucleon twist-3 parton distribution function e(x). Data have been collected in the Hall-B at Jefferson Lab by impinging a 5.498-GeV electron beam on a liquid-hydrogen target, and reconstructing the scattered electron and the pion pair with the CLAS detector. One-dimensional projections of the A_{LU}^{sinϕ_{R}} moments are extracted for the kinematic variables of interest in the valence quark region. The understanding of dihadron production is essential for the interpretation of observables in single-hadron production in semi-inclusive DIS, and pioneering measurements of single-spin asymmetries in dihadron production open a new avenue in studies of QCD dynamics.

Extraction of Beam-Spin Asymmetries from the Hard Exclusive π

We have measured beam-spin asymmetries to extract the sinϕ moment A_{LU}^{sinϕ} from the hard exclusive e[over →]p→e^{'}nπ^{+} reaction above the resonance region, for the first time with nearly full coverage from forward to backward angles in the center of mass. The A_{LU}^{sinϕ} moment has been measured up to 6.6 GeV^{2} in -t, covering the kinematic regimes of generalized parton distributions (GPD) and baryon-to-meson transition distribution amplitudes (TDA) at the same time. The experimental results in very forward kinematics demonstrate the sensitivity to chiral-odd and chiral-even GPDs. In very backward kinematics where the TDA framework is applicable, we found A_{LU}^{sinϕ} to be negative, while a sign change was observed near 90° in the center of mass. The unique results presented in this Letter will provide critical constraints to establish reaction mechanisms that can help to further develop the GPD and TDA frameworks.

Exploring the Structure of the Bound Proton with Deeply Virtual Compton Scattering.

In the past two decades, deeply virtual Compton scattering of electrons has been successfully used to advance our knowledge of the partonic structure of the free proton and investigate correlations between the transverse position and the longitudinal momentum of quarks inside the nucleon. Meanwhile, the structure of bound nucleons in nuclei has been studied in inclusive deep-inelastic lepton scattering experiments off nuclear targets, showing a significant difference in longitudinal momentum distribution of quarks inside the bound nucleon, known as the EMC effect. In this Letter, we report the first beam spin asymmetry (BSA) measurement of exclusive deeply virtual Compton scattering off a proton bound in ^{4}He. The data used here were accumulated using a 6 GeV longitudinally polarized electron beam incident on a pressurized ^{4}He gaseous target placed within the CLAS spectrometer in Hall-B at the Thomas Jefferson National Accelerator Facility. The azimuthal angle (ϕ) dependence of the BSA was studied in a wide range of virtual photon and scattered proton kinematics. The Q^{2}, x_{B}, and t dependencies of the BSA on the bound proton are compared with those on the free proton. In the whole kinematical region of our measurements, the BSA on the bound proton is smaller by 20% to 40%, indicating possible medium modification of its partonic structure.

First Measurements of the Double-Polarization Observables F, P, and H in ω Photoproduction off Transversely Polarized Protons in the N

First measurements of double-polarization observables in ω photoproduction off the proton are presented using transverse target polarization and data from the CEBAF Large Acceptance Spectrometer (CLAS) FROST experiment at Jefferson Lab. The beam-target asymmetry F has been measured using circularly polarized, tagged photons in the energy range 1200-2700 MeV, and the beam-target asymmetries H and P have been measured using linearly polarized, tagged photons in the energy range 1200-2000 MeV. These measurements significantly increase the database on polarization observables. The results are included in two partial-wave analyses and reveal significant contributions from several nucleon (N^{*}) resonances. In particular, contributions from new N^{*} resonances listed in the Review of Particle Properties are observed, which aid in reaching the goal of mapping out the nucleon resonance spectrum.

Metabolic Effects of Androgen-associated Body Mass in Klinefelter Syndrome.

Patients with Klinefelter Syndrome (KS) are at increased risk for both diabetes and cardiovascular disease. While the anabolic effects of androgen replacement therapy may be associated with weight gain in such patients, the metabolic effects of this weight gain are unknown. Since untreated KS represents a natural example of androgen deprivation, we hypothesized that KS patients who are receiving androgen replacement would have a healthier metabolic risk factor profile, in addition to an increased Body Mass Index (BMI), relative to patients who are not receiving androgen replacement. Using de-identified data collected from Health Facts (a national, consolidated, and relational database of Electronic Health Records), we identified 2,447 adult patients with an ICD-9 billing code for KS. Of these, 262 patients were included in this study based on available anthropometrics, metabolic profiles, and information about androgen replacement. Multiple linear regression analysis was performed using BMI as the dependent variable in a model that included age, androgen replacement therapy (yes or no), A1C, blood pressure, and fasting lipids. Post-hoc comparisons were made using frequency analysis and the unpaired Student's t-test. There were 81 patients with KS who received androgen replacement and 181 patients who did not. In multiple regression, only androgen therapy was positively and significantly associated with BMI while adjusting for other risk factors (p=0.03). Post-hoc comparison of metabolic risk factors revealed no other differences between patients who received androgen replacement and those who did not. These data suggest that androgen replacement therapy in Klinefelter Syndrome is associated with increased BMI, but this increase does not appear to exert a detrimental effect on other metabolic risk factors in this condition.

Predictors of Physical Fitness among Southwestern Native American Adolescents at Risk for Diabetes.

The prevalence of obesity is increasing among children nationally. Native American children from Zuni Pueblo appear to be at increased risk for obesity, which also increases the risk for the metabolic syndrome, diabetes, and cardiovascular disease. While exercise and physical fitness can prevent or forestall these developments, predictors of physical fitness in this population are unknown. Forty-seven Native American adolescents completed four aspects of the Presidential Fitness Challenge (push-ups, sit-ups, step-ups, and timed walking) during screening for another study, and fitness was empirically summarized with a Presidential Fitness Index. Correlative analyses were subsequently performed to elucidate predictors of fitness. Age was the only independent predictor of the Presidential Fitness Index. Other variables that were not found to be independent predictors included BMI percentile, waist circumference, fat free mass, total body fat, and HDL cholesterol. Among adolescent Southwest Native Americans, older children performed better on the Presidential Fitness Challenge. Additionally, BMI was not found to be an independent predictor of fitness.

Cellular distribution and amount of chromogranin A in bovine endocrine pancreas.

We determined the cellular distribution and the amount of chromogranin A in endocrine cells of bovine pancreas using a polyclonal antibody against bovine adrenomedullary chromogranin A. The relative amounts of chromogranin A in the different cells of the endocrine pancreas were determined by computer-assisted analyses of the optical densities of the immunoreactivities in the stained sections. More than 80% of the immunoreactive chromogranin A was located in the pancreatic B-cells. In immunoblots of acid tissue extracts, only one chromogranin A band (MW 74 KD) was observed. Quantification of the immunoblots revealed that 3 micrograms of chromogranin A and 918 micrograms of insulin were present per gram pancreas (wet weight), equivalent to a molar ratio of 460 mumol chromogranin A per mol insulin.

Chromogranin A in the pancreatic islet: cellular and subcellular distribution.

Chromogranin A (CGA) is the major soluble protein within secretory vesicles of chromaffin cells. A polyclonal antiserum was raised against bovine CGA and characterized in two-dimensional immunoblots. Cellular and subcellular distribution of CGA in bovine pancreatic islet was investigated by immunocytochemistry. At the light microscopic level, CGA-like immunoreactivity was found in the same cells that react with antibodies against insulin, glucagon, and somatostatin. A minority of cells containing pancreatic polypeptide also showed faint immunostaining. At the ultrastructural level (protein A-gold technique), CGA-like immunoreactivity was confined exclusively to the secretory vesicles. Whereas the hormones were localized mainly in the central part of the secretory vesicles, CGA was present predominantly in the periphery. These findings indicate that a CGA-like protein is a regular constituent of the matrix of secretory vesicles in pancreatic endocrine cells.

K-complexes and sleep spindles before transient activation during sleep.

Six subjects spent three consecutive nights in the sleep laboratory. Activation phases (PATs), spontaneous K-complexes, and sleep spindles were visually detected in sleep stages 2 and 3 for nights 2 and 3. The K-complex rate was significantly greater in the 10 sec prior to the PATs than at any other time spent in stage 2 or 3. K-complexes associated with sheep spindles occurred significantly less frequently during the epochs just preceding the PATs. In all subjects, there was a sharp increase of sleep spindles associated with K-complexes when PATs did not follow within 10 sec. These results suggest that spontaneous K-complexes and sleep spindles act antagonistically with respect to the occurrence of PATs. These two phasic events are significantly related to regulating the probability of occurrence of PATs in sleep stages 2 and 3; K-complexes may reflect an organismic state leading towards PAT, whereas sleep spindles may inhibit the occurrence of PAT.

Platypnea-orthodeoxia syndrome related to an aortic aneurysm combined with an aneurysm of the atrial septum.

We report the case of a 71-year-old man bearing a severe right-to-left shunt through a patent foramen ovale in the absence of elevated right-sided heart or pulmonary artery pressures. He presented with platypnea-orthodeoxia syndrome, but he had no pulmonary or extracardiac diseases that are known to be associated with this syndrome. Chest radiography showed a bulky aneurysm of the thoracic aorta. A peripheral contrast transesophageal echocardiography demonstrated a large right-to-left shunt through a patent foramen ovale. In addition, the atrial septum was severely deformed by an aneurysm including this patent foramen ovale. We hypothesized that the opening of the foramen ovale was the result of a mechanical deformation of the atrial septum by two contributing factors: the aneurysm of the thoracic aorta and the aneurysm of the septum itself.

[Hypoxia and pulmonary circulation. The importance of hypoxia in pulmonary arterial hypertension of chronic obstructive bronchopneumopathies]. / Hypoxie et circulation pulmonaire. Importance de l'hypoxie dans l'hypertension artérielle pulmonaire des bronchopneumopathies chroniques obstructives.

In chronic airflow obstruction (CAO), there are grounds for distinguishing between the effects of acute alveolar hypoxia and those of chronic hypoxia. Acute hypoxia leads, in healthy subjects, to pulmonary vasoconstriction. In patients with CAO, there is however a great variability in the pulmonary vascular response to hypoxia. Chronic hypoxia leads in the long term to structural modifications in the pulmonary vessels (arteriolar muscularization, hypertrophy of the small arterial muscles, and intimal fibrosis), which are similar enough to those seen in residents at high altitude and which lead to an elevation of the pulmonary vascular resistance. These structural changes are potentially reversible but one does not know up to which point they are. This potential reversibility represents one of the justifications of long term oxygen therapy in these patients. The pulmonary arterial hypertension of CAO is generally moderated; it evolves slowly over years and years in the majority of cases; it certainly doesn't merit to be treated at any cost. Up to the present, pulmonary vasodilators have given rather disappointing results. Prolonged oxygen therapy (for greater than 16 hours in 24), which improves in other respects the expectation of life in patients is currently the most logical treatment for pulmonary hypertension in CAO.

[M-mode echocardiography in the diagnosis of pulmonary arterial hypertension in chronic respiratory disorders]. / Apport de l'échocardiographie de mode M au diagnostic de l'hypertension artérielle pulmonaire dans les affections respiratoires chroniques.

Right heart catheterisation (reference method) and M-mode echocardiography were performed in 90 patients with chronic respiratory failure (73 BPCO-chronic airflow obstruction and 17 non-BPCO). The aim of this study was to assess the place of echo-cardiography in the diagnosis and assessment of pulmonary arterial hypertension (HTAP) and/or right ventricular hypertrophy (HVD). The results are somewhat deceptive; first as reliable measurements were impossible in 20% of cases (due to airways distension), then because the sensibility of the method is only 75% (only 62.2% in the group with moderate HTAP with a mean pulmonary artery pressure (PAP) between 21 and 30 mmHg, where as the specificity was satisfactory (87.5%). The best coefficient of linear correlation was observed between the PAP and the end-diastolic diameter of the right ventricle (DTDVD) (r = 0.52; p less than 0.001). Such a correlation does not allow for a prediction of an exact level of PAP in individual cases. The combination of 3 non-invasive methods (ECG, Echo-cardiography and myocardial scintigraphy) allows for an excellent overall sensibility (91.7%) but to the detriment of the specificity (66.6% only).

[Value of the measurement of the alveolo-arterial PO2 difference in moderate hyperoxia (FIO2 = 0.40) in chronic respiratory insufficiency]. / Intérêt de la mesure de la différence alvéolo-artérielle de PO2 en hyperoxie modérée (FIO2 = 0,40) dans l'insuffisance respiratoire chronique.

Alveolo-arterial difference in PO2 (AaDO2) during moderate hyperoxia (FIO2 = 0.40) and shunt-effect (Qs/Qt) were measured in 219 patients with chronic lung disease of various aetiologies. In particular, the series included 79 chronic bronchitics, 35 cases of "primary" emphysema, 40 cases of sarcoidosis and 36 cases of diffuse interstitial pulmonary fibrosis ( DIPF ). Alveolar PO2 was calculated from the equation of alveolar air. Ventilatory parameters were measured under stable conditions using a Fleisch metabograph . Shunt-effect (in moderate hyperoxia) was calculated from the classical equation. AaDO2 in chronic bronchitis was on average 118.3 +/- 30.7 mmHg, significantly higher (p less than 0.005) than in the emphysema patients: 99.2 +/- 22.3 mmHg. The same difference between the two groups was found for shunt-effect (p less than 0.005). In sarcoidosis, AaDO2 and Qs/Qt were only slightly raised on average: 83.6 +/- 22.0 mmHg and 7.2 +/- 3.7% respectively. By contrast, in DIPF , AaDO2 was very high (124.9 +/- 35.7 mmHg) as was Qs/Qt (14.8 +/- 6.9%). The measurement (in moderate hyperoxia) of AaDO2 and Qs/Qt, which are fairly representative of ventilation-perfusion inequalities, may thus make a contribution to the physiopathological differentiation between chronic bronchitis and emphysema. The frank increase in AaDO2 and Qs/Qt in DIPF emphasises the importance of ventilation-perfusion inequalities in the development of hypoxaemia in such patients. For all the cases studied, there was a very satisfactory correlation between AaDO2 in moderate hyperoxia and PaO2 at rest in ordinary air (r = -0.64, p less than 0.001). Similarly, there was a satisfactory correlation between Qs/Qt in moderate hyperoxia and PaO2 at rest in ordinary air (r = -0.53, p less than 0.01).