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.

First Measurement of Λ Electroproduction off Nuclei in the Current and Target Fragmentation Regions.

We report results of Λ hyperon production in semi-inclusive deep-inelastic scattering off deuterium, carbon, iron, and lead targets obtained with the CLAS detector and the Continuous Electron Beam Accelerator Facility 5.014 GeV electron beam. These results represent the first measurements of the Λ multiplicity ratio and transverse momentum broadening as a function of the energy fraction (z) in the current and target fragmentation regions. The multiplicity ratio exhibits a strong suppression at high z and an enhancement at low z. The measured transverse momentum broadening is an order of magnitude greater than that seen for light mesons. This indicates that the propagating entity interacts very strongly with the nuclear medium, which suggests that propagation of diquark configurations in the nuclear medium takes place at least part of the time, even at high z. The trends of these results are qualitatively described by the Giessen Boltzmann-Uehling-Uhlenbeck transport model, particularly for the multiplicity ratios. These observations will potentially open a new era of studies of the structure of the nucleon as well as of strange baryons.

Observation of Correlations between Spin and Transverse Momenta in Back-to-Back Dihadron Production at CLAS12.

We report the first measurements of deep inelastic scattering spin-dependent azimuthal asymmetries in back-to-back dihadron electroproduction in the deep inelastic scattering process. In this reaction, two hadrons are produced in opposite hemispheres along the z axis in the virtual photon-target nucleon center-of-mass frame, with the first hadron produced in the current-fragmentation region and the second in the target-fragmentation region. The data were taken with longitudinally polarized electron beams of 10.2 and 10.6 GeV incident on an unpolarized liquid-hydrogen target using the CLAS12 spectrometer at Jefferson Lab. Observed nonzero sinΔϕ modulations in ep→e^{'}pπ^{+}X events, where Δϕ is the difference of the azimuthal angles of the proton and pion in the virtual photon and target nucleon center-of-mass frame, indicate that correlations between the spin and transverse momenta of hadrons produced in the target- and current-fragmentation regions may be significant. The measured beam-spin asymmetries provide a first access in dihadron production to a previously unexplored leading-twist spin- and transverse-momentum-dependent fracture function. The fracture functions describe the hadronization of the target remnant after the hard scattering of a virtual photon off a quark in the target particle and provide a new avenue for studying nucleonic structure and hadronization.

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.

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.

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

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.

Temporización inmediata de implantes unitarios en la maxila posterior / Immediate temporization of posterior maxilla single tooth implant

Propósito: El presente artículo es un estudio prospectivo de las tasas de éxito implantaria y de las complicaciones mecánicas y biológicas en el tratamiento rehabilitador implanto-asistido del sector posterior de la maxila, mediante provisionalización inmediata. Material y Método: El estudio clínico observó a 21 sujetos desdentados parciales unitarios del sector posterior maxilar, con reborde cicatrizado y antagonista dentario natural, por un período de 6 meses, en los que se insertaron implantes cónicos roscados de conexión interna, con tratamiento de superficie, temporizados inmediatamente después de insertados en el hueso maxilar, mediante la confección de una corona de resina acrílica sobre un pilar temporal de titanio atornillada directa al implante, dejados sin contactos dentarios durante la máxima intercuspidación (MIC) y movimientos excéntricos mandibulares. Todas las restauraciones fueron observadas durante un período de 6 meses, evaluando tasa de éxito implantario, complicaciones biológicas y mecánicas. Resultados: Se insertaron 25 implantes en 21 pacientes, obteniéndose un valor promedio de inserción de torque quirúrgico de 45.6 Nt. Durante el período de observación clínico se presentó un 100 por ciento de éxito de sobrevida implantario, no se detectaron complicaciones biológicas, pero sí se presentaron complicaciones mecánicas por fractura de una cúspide vestibular de una restauración provisional acrílica y dos aflojamientos de tornillos. Conclusiones: La temporización unitaria mediante provisorio atornillado es un protocolo predecible y confiable que permite el proceso de oseointegración y la coexistencia en salud de tejido periimplantario y su sistema protésico.

Purpose: This article is a prospective study of implant success rates and of mechanical and biological complications in the assisted-implant rehabilitation treatment of the posterior maxilla by immediate temporization. Material and Methods: The clinical study observed 21 partially edentulous subjects with lip scar and antagonistic natural teeth in the posterior maxilla for a period of 6 months in which conical threaded internal implant connections were inserted with a surface treatment and timed immediately after being inserted into the jawbone by producing an acrylic resin crown on a temporary titanium abutment screwed directly into the implant and left without tooth contacts during the Maximal Intercuspal (MIC) and mandibular eccentric movements. All restorations were observed over a period of 6 months evaluating implant success rate and biological and mechanical complications. Results: 25 implants were inserted into 21 patients yielding an average surgical insertion torque of 45.6 Nt. During the clinical observation there was 100 percent success of implant survival. No biological complications were detected, but there were mechanical complications - a buccal cusp fracture of an acrylic provisional restoration and two screws loosening. Conclusions: The unit temporization by temporary screwing is a predictable and reliable protocol that allows osseointegration and the coexistence in the health of peri-implant tissue and its prosthetic system.

Experiencia y significado del proceso de edentulismo de adultos mayores, atendidos en un consultorio del servicio público chileno / Experience and significance of the edentulous process of older adults who attended a chilean public service office

En Santiago de Chile la prevalencia de desdentados totales en individuos mayores de 65 años es de 33.84 por ciento, es decir uno de cada tres santiaguinos de la 3° edad, es portador de prótesis totales. Prevalencia similar a la encontrada en países desarrollados. A partir de esta investigación se pretende comprender cual es la experiencia, significados y valoración del proceso de edentulismo de adultos mayores, tratados en un servicio de salud público, y sus familiares más cercanos; para entender cuales son sus vivencias y padecimientos; para poder entregarle una atención más completa, significativa y eficiente, orientada a lo que las personas perciben como importante. Tipo de estudio: El presente trabajo de investigación se desarrolló dentro de un paradigma naturalista cualitativo, por cuanto está interesado en conocer el fenómeno desde el propio marco de referencia del actor social; fundamentado en la realidad, de carácter exploratorio y enfoque fenomenológico. Selección de participantes: Se seleccionó a 11 hombres y 9 mujeres; adultos mayores, desdentados totales del Centro de Salud Familiar Garín, y a un familiar directo. Se consideró para esta investigación la aplicación de entrevistas semi estructuradas y grupo focal. Resultados: El presente estudio de investigación cualitativa, entregó relevante información, en la forma como piensa siente y vivencia el problema del edentulismo el propio actor social; la que pude ser considerada en la elaboración de nuevos proyectos y programas desarrollados especialmente para esta población; así como también, en el campo educacional.

In Santiago, Chile the prevalence of Edentulous in individuals over 65 years of age is 33.84 percent; this is to say that one third of Santiago s senior citizens wear dentures. Prevalence similar to this can be found in developed countries. From this research, the aim is to understand the experience, significance and assessment of the Edentulous process of senior citizens that are treated in public health service and to also understand the experiences and sufferings of their immediate families; To be able to give fuller, meaningful, and efficient attention by focusing on what people perceive as important. Type of study: This research work was developed within a qualitative naturalistic paradigm, to know the phenomenon from the interest point of the framework itself, the social actor; based on reality, exploratory and phenomenological approach. Selection of participants: 11 men and 9 women were selected; Elderly, all edentulous patients (and their immediate families) from the Garín Family Health Center. The application of semi-structured interviews and focus groups were considered for this research. Results: The qualitative research study delivered relevant information in the way that the Edentulous social actor himself thinks, feels and experiences the problem. This could be considered in the development of new projects and programs developed specifically for this population. As well as in the educational field.

Protocolo protésico - quirúrgico en temporización inmediata de dientes unitarios, utilizando una cubeta multifuncional desmontable / Prosthetic protocol - surgery in the immediate temporization of a single tooth using a multifunctional removable tray

Propósito: El presente reporte clínico es la descripción de un protocolo protésico - quirúrgico que permite la visualización directa del sitio operatorio y el correcto posicionamiento protésico - implantario de una corona temporal atornillada, construida inmediatamente de insertado el implante. Material y métodos: Se seleccionaron 10 pacientes del programa de especialización en implantologia bucomaxilofacial de la Universidad de Chile, cuyo criterio de inclusión principal fue ser desdentado parcial unitario posterior, con antagonista dentario natural. Como protocolo diagnóstico se solicitaron exámenes de laboratorio, exámenes radiograficos y se registraron sus arcos dentarios con impresiones de estudio a fin de obtener modelos de yeso, los que fueron posicionados en un articulador semiajustable tipo Whip Mix, donde se confeccionó un encerado diagnóstico del diente a reemplazar, libre de contacto oclusal en máxima intercuspidación (MIC) y en los movimientos excursivos mandibulares. Basado en el encerado de diagnóstico se diseño una cubeta multifuncional desmontable (U. de Chile) cuya característica fundamental es que fusiona una guía quirúrgica y una guía de montaje protésico, para una correcta temporización inmediata. El procedimiento se inicia mediante un colgajo de espesor total, posicionamiento en boca de la guía multifuncional en fase quirúrgica, para permitir el fresado del lecho implantario y la inserción implantaria. El lecho quirúrgico es suturado mediante una seda negra trensada y se confecciona en forma inmediata una corona temporal atornillada utilizando la guía multifuncional en fase de carga protésica. Resultados: Se instalaron un total de 12 implantes Renova Tapered (Lifecore) utilizando la cubeta multifuncional la cual facilitó la direción del fresado y la contrucción de sus respectivas coronas temporales de resina acrilica, no segmentadas atornilladas. Conclusiones: Con las limitaciones de este estudio, la fusión de ambos procedimientos brinda...

Purpose: This clinical report is the description of a prosthetic protocol - surgery which allows direct visualization of the operative site and the correct positioning of the prosthetic-implantation of a screw retained temporary crown constructed immediately following the insertion of the implant. Methods: 10 patients, whose main inclusion criterion was having a partially edentulous posterior unit with an opposing natural tooth, were selected from the specialized program of Maxillofacial Implantology at the University of Chile. As diagnostic protocol was requested, laboratory tests, radiographic examinations and impressions of dental arches were recorded in order to obtain plaster models for the study and which were positioned in a semi-adjustable articulator type Whip Mix, which produced a diagnostic wax-up tooth replacement, free of occlusal contact in the maximal intercuspal (MIC) and mandibular excursions. Based on the diagnostic wax-up one can design a multi-functional removable tray (U. de Chile), whose key feature is that it merges a surgical guide and a prosthetic assembly guide for the correct immediate temporization. The procedure starts with a full thickness flap positioned in the mouth of the multi-functional guide of the surgical phase to allow the implant site drilling and implant insertion. The surgical site is sutured with black braided silk and you immediately draw up the screw retained temporary crown using the multi-functional guide in the prosthetic loading phase. Results: A total of 12 Renova Tapered implants (Lifecore) were installed using the multi-functional tray which provided the direction of the drilling and construction of its acrylic- resin temporary crowns without segmented screws. Conclusions: With the limitations of this study, the merging of both procedures provide a predictable safe alternative treatment that is quick and easy to implement for the clinician allowing the immediate temporization of the implant. Technical Report.

Melatonin-like immunoreactivity in the pineal gland of the cow: an immunohistochemical study.

With a view to checking the presence of melatonin in the pineal gland of the cow, in the present work we used six adult animals, ranging in age from one to six years, which were sacrificed at dawn. Sections of 6 micro m thickness of Bouin-fixed and paraffin-embedded pineal glands were incubated in an anti-melatonin serum, which was provided by the Institute for Molecular and Cellular Recognition, Gunma University, Maebshi, Japan. After incubation and successive washings in PBS, some of the sections were treated with the avidin-biotin-peroxidase complex (ABC) technique using antisera from Sigma, and developed with the method of Graham and Karnovsky (which employs 3,3'-diaminobenzidine and H2O2 as developer). Other sections were incubated in a goat-anti-rabbit IgG (H+L) bound to fluorochrome Cy5 for immunofluorescence studies. An intense reaction for melatonin was observed in the cytoplasm but not in the nucleus of melatonin secreting pinealocytes located in peripheral and intermediate zones of the pineal gland. Immunoabsorption of the antimelatonin primary antibody with melatonin at a dilution of 10 mM per 0.1 ml of serum prevented the reaction, as happened when any of the antisera used in the procedure were used. Immunoabsorption of anti-melatonin serum with different amounts of bovine albumin (ranging between 1/5 to 1/50) failed to inhibit the immunoreactivity. When a bovine anti-albumin antibody was employed, working with the above methods, no immunoreaction was detected. Our data suggest that the pinealocytes of cows sacrificed at dawn contain immunoreactive melatonin.

Cellular proliferation in the rat pineal gland during postnatal development.

To establish a possible correlation between the rate of cellular proliferation and already documented functional and morphological characteristics of the rat pineal gland during postnatal development, the bromodeoxyuridine labelling method was used to evaluate the fraction of cells at the S phase of the cell cycle in paraffin sections from 1-, 7-, 14- and 28-day-old rats. Numerical density, taken as an indirect measure of cell hypertrophy, was also evaluated. During the first week after birth the percentage of S phase-cells in the rat pineal gland sharply decreased from around 9% to 1.3%. A smaller but also significant decrease was found from the 7th to the 14th postnatal day where S phase cells were less than 0.5% of all pineal cells. A very low percentage was also seen in samples from 28-day-old rats. Numerical density, namely, the total number of cells per surface unit of pineal section, decreased from birth to the end of the first month. This decrease was also steeper from birth to the 7th postnatal day than at any other period of the study. These results support the idea that a strong expansion of the cellular population of the rat pineal gland precedes morphological and functional maturation and opens the way to further exploration of the relationship between functional and proliferative responses of the pineal gland.

Cellular proliferation and/or differentiation can condition modifications in the expression of AgNORs in rat anterior pituitary cells during growth.

The expression of argyrophilic nucleolar organizer regions (AgNORs) was studied in the anterior lobe of the hypophysis of 1-, 7-, 14-, 28- and 80-day-old rats. Mean area and numbers of AgNORs per nucleus decreased during this period with a simultaneous increase of both nuclear area and mean AgNOR-particle area. Comparison of our data on AgNOR expression with previously reported data on the proliferative activity and cell maturation and differentiation of anterior pituitary cells during a similar period led us to conclude that, at least in our experimental model, variations in the expression of AgNORs are more related to phenomena of cellular maturation than to proliferative activity.

Immunocytochemical study of the epithelial lining of naturally occurring cysts in the rat intermediate lobe.

An immunocytochemical study of the epithelial lining of naturally occurring cysts in the rat intermediate lobe (IL) has been carried out. Paraffin-embedded sections, in which cysts were identifiable, were treated either with anti-serotonin or anti-S-100 protein sera. S-100-positive cells were intermingled with glandular cells surrounding the cyst lumen. These S-100-positive cells sent slender cytoplasmic processes as if to cover the apical surface of neighbouring cells. Rarely were 5-HT-immunopositive cells seen in the cyst epithelial lining. Most cells of the marginal layer of the IL were found reactive either to an S-100 or a-5-HT serum. The presence of an epithelial lining positive to S-100 protein sera is in keeping with the notion that cysts in the IL might form as evaginations of the epithelial lining of the pituitary cleft. The lack of correspondence between 5-HT-positive cells in the marginal layer and the cyst lining is controversial. A peculiar spatial relationship of 5-HT cells with the vascular network of the IL is suggested.

Serotonin immunoreactivity in the intermediate lobe of the rat pituitary.

Immunocytochemical staining for serotonin (5-HT) in paraffin-embedded sections of rat pituitary resulted in the localization of reactive nerve fibres and cell bodies in the intermediate lobe. Immunostaining was also found in the anterior and posterior lobes. Labelled nerve fibres appear to enter the intermediate lobe from the neural lobe through the interlobular spaces. These fibres are relatively scarce and lightly stained. Neuroglandular contacts were identified between varicose nerve endings containing serotonin and immunoreactive perykarion. It is not clear whether intermediate lobe cells produced 5-HT themselves or, alternatively, these cells take in 5-HT from serotoninergic nerve terminals.