The atomic nucleus is composed of two different kinds of fermions: protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority of ...fermions (usually neutrons) to have a higher average momentum. Our high-energy electron-scattering measurements using 12C, 27Al, 56Fe, and 208Pb targets show that even in heavy, neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few-body systems to neutron stars and may also be observable experimentally in two-spin–state, ultracold atomic gas systems.
The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of ...polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-Z target. Positron polarization up to 82% have been measured for an initial electron beam momentum of 8.19 MeV/c, limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community.
Measuring DVCS on a neutron target is a necessary step to deepen our understanding of the structure of the nucleon in terms of Generalized Parton Distributions (GPDs). The combination of DVCS ...observables on neutron and proton targets allows to perform a flavor decomposition of the Compton Form Factors (CFFs), which are related to integrals of GPDs. Moreover, neutron-DVCS plays a complementary role to DVCS on a transversely polarized proton target in the determination of the CFF of the GPD
E
, the least known and constrained GPD that enters Ji’s angular momentum sum rule. A measurement of the beam-charge asymmetry (BCA) in the
e
±
d
→
e
±
n
γ
(
p
)
reaction can significantly impact the experimental determination of the real CFFs of the
E
and, to a lesser extent,
H
~
CFFs.
The understanding of Quantum Chromodynamics (QCD) at large distances still remains one of the main outstanding problems of nuclear physics. Studying the internal structure of hadrons provides a way ...to probe QCD in the non-perturbative domain and can help us unravel the internal structure of the most elementary blocks of matter. Jefferson Lab (JLab) has already delivered results on how elementary quarks and gluons create nucleon structure and properties. The upgrade of JLab to 12 GeV will allow the full exploration of the valence-quark structure of nucleons and the extraction of real three-dimensional pictures. I will present recent results and review the future experimental program at JLab.
Background and ImportanceThis retrospective study aimed to assess the utility of renal glomerular filtration rate (GFR) estimation formulas, including Cockcroft-Gault (CG), Modification of Diet in ...Renal Disease (MDRD-4), and Chronic Kidney Disease Epidemiology (CKD-EPI), in the pharmacokinetic monitoring of vancomycin.Aim and ObjectivesThe study aimed to evaluate the correlation between estimated GFR using different formulas and the actual clearance of vancomycin in patients, providing valuable insights for pharmacokinetic monitoring and dosing adjustments.Material and MethodsRetrospective study (October 2022 to March 2023) on patients monitored by the Clinical Pharmacokinetics Unit during vancomycin treatment. Inclusion criteria: age ≥ 18, ≥ two vancomycin trough plasma concentrations (Cmin), and stable serum creatinine (+/- 0.5 mg/dL) during monitoring. Recorded variables: gender, age, weight (kg), height (cm), serum creatinine mg/dL), estimated glomerular filtration rate (eGFR) (mL/min) using various formulas, observed vancomycin Cmin (mcg/mL), and predicted Cmin (mcg/mL) based on Bayesian adjustment (software: Mw-Pharm++®). Linear regression analysed the relationship between initial estimated vancomycin plasma clearance (Clp) using eGFR data and patient‘s actual Clp obtained through Bayesian estimation (considering monitored vancomycin concentrations).ResultsA total of 34 patients were recruited (65.70% males, mean age ± standard deviation: 68.06 ± 16.89 years). The mean estimated glomerular filtration rate (GFR) values were: 84.44 ± 49.87mL/min, 116.23 ± 52.95mL/min, 91.53 ± 28.22mL/min for the CG, MDRD-4, and CKD-EPI formulas, respectively. The mean observed vancomycin Cmin in the second analytical determination was 16.13 ± 6.56 mcg/mL. The mean predicted Cmin values were 17.15 ± 8.08 mcg/mL, 14.03 ± 8.26 mcg/mL, and 14.57 ± 7.56 mcg/mL for the CG, MDRD-4, and CKD-EPI formulas, respectively. Based on the coefficients of determination calculated from the regression lines, 83%, 76%, and 86% of the variations found in the actual vancomycin clearance can be explained by variations in the estimated clearance using GFR data obtained with the CG, MDRD-4, and CKD-EPI formulas, respectively.Conclusion and RelevanceIn this study, the Cockcroft-Gault and CKD-EPI formulas exhibited better correlation with actual vancomycin clearance compared to MDRD-4. The findings suggest a potential risk of overdosing when using MDRD-4. Although initial vancomycin dosing based on estimated GFR formulas provides a reasonable approach, pharmacokinetic monitoring of plasma concentrations remains a safer approach for antibiotic dosing.References and/or AcknowledgementsConflict of InterestNo conflict of interest.
Background and ImportanceCurrent literature supports that the use of H2 antihistamines in paclitaxel-containing regimens is not essential, although publications are scarce.1 Aim and ObjectivesTo ...determine the incidence of hypersensitivity reactions (HRs) during paclitaxel infusion after the withdrawal of ranitidine from the market.Material and MethodsObservational, retrospective and descriptive study in which patients undergoing chemotherapy with paclitaxel-containing schemes for adjuvant (ABC) and neoadjuvant (NBC) breast cancer, cervical cancer (CC), ovarian (OC) and endometrial (EC) were included. The study period was from 2 February 2022 (cessation of marketing of ranitidine) to 31 August 2023.HRs were analysed after modification of the premedication protocol, which included the same treatment guidelines, excluding ranitidine.Variablesage, sex, type of neoplasm, line of treatment, treatment schedule, administration time, premedication, HRs and measure adopted.Data sourcecomputerised medical records and electronic prescribing programme.ResultsA total of 493 administrations of paclitaxel were infused to 68 patients (100% female) with a median age of 64 years 31–89. 20% corresponded with ABC, 29% OC, 14% CC, 11% EC and 26% NBC. Sixty-seven percent of patients were first-line.Six HRs were observed during the first or second cycle. Three (50%) were related to paclitaxel administration, one in ABC (paclitaxel 80 mg/m2 weekly over 1 hour), one in OC (paclitaxel 175 mg/m2 over 3 hours) and one in EC (paclitaxel 175 mg/m2 over 3 hours). The remaining three were related to the administration of carboplatin in patients on OC.HRs appeared in patients aged 43–67 years. One required discontinuation of treatment, the rest were given premedication the day before the cycle and increased infusion time.Conclusion and RelevanceThe use of premedication protocols without H2 antihistamines appears to be a safe practice. Our study has limitations in terms of sample size. However, it is important to know the role of these drugs and it is necessary to involve the pharmacist in the development of hospital protocols to identify patients to benefit from these drugs.References and/or Acknowledgements1. Gelderblom H, Zwaveling J. No need for H2-antagonists in premedication regimens for paclitaxel infusions: less is more. Br J Cancer. 2021;124(10):1613–4.No conflict of interest.Conflict of InterestNo conflict of interest.
Short Range Correlations (SRCs) have been identiffed as being responsible for the high momentum tail of the nucleon momentum distribution, n(k). Hard, short-range interactions of nucleon pairs ...generate the high momentum tail and imprint a universal character on n(k) for all nuclei at large momentum. Triple coincidence experiments have shown a strong dominance of np pairs, but these measurements involve large final state interactions. This paper presents the results from Jefferson Lab experiment E08014 which measured inclusive electron scattering cross-section from Ca isotopes. Here, by comparing the inclusive cross section from 48Ca to 40Ca in a kinematic region dominated by SRCs we provide a new way to study the isospin structure of SRCs.
We present deeply virtual π0 electroproduction cross-section measurements at xB=0.36 and three different Q2 values ranging from 1.5 to 2 GeV2, obtained from Jefferson Lab Hall A experiment E07-007. ...The Rosenbluth technique is used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component and, thus, is far from the asymptotic limit predicted by perturbative quantum chromodynamics. Nonetheless, an indication of a nonzero longitudinal contribution is provided by the measured interference term σLT. Results are compared with several models based on the leading-twist approach of generalized parton distributions (GPDs). In particular, a fair agreement is obtained with models in which the scattering amplitude includes convolution terms of chiral-odd (transversity) GPDs of the nucleon with the twist-3 pion distribution amplitude. This experiment, together with previous extensive unseparated measurements, provides strong support to the exciting idea that transversity GPDs can be accessed via neutral pion electroproduction in the high-Q2 regime.
The cross section for coherent ω-meson photoproduction off the deuteron has been measured for the first time as a function of the momentum transfer t=(Pγ−Pω)2 and photon energy Eγ using the CLAS ...detector at the Thomas Jefferson National Accelerator Facility. The cross sections are measured in the energy range 1.4<Eγ<3.4 GeV. A model based on ω−N rescattering is consistent with the data at low and intermediate momentum transfer, |t|. For 2.8<Eγ<3.4 GeV, the total cross-section of ω−N scattering, based on fits within the framework of the Vector Meson Dominance model, is in the range of 30–40 mb.
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