While mean-field approximations, such as the nuclear shell model, provide a good description of many bulk nuclear properties, they fail to capture the important effects of nucleon–nucleon ...correlations such as the short-distance and high-momentum components of the nuclear many-body wave function1. Here, we study these components using the effective pair-based generalized contact formalism2,3 and ab initio quantum Monte Carlo calculations of nuclei from deuteron to 40Ca (refs. 4–6). We observe a universal factorization of the many-body nuclear wave function at short distance into a strongly interacting pair and a weakly interacting residual system. The residual system distribution is consistent with that of an uncorrelated system, showing that short-distance correlation effects are predominantly embedded in two-body correlations. Spin- and isospin-dependent ‘nuclear contact terms’ are extracted in both coordinate and momentum space for different realistic nuclear potentials. The contact coefficient ratio between two different nuclei shows very little dependence on the nuclear interaction model. These findings thus allow extending the application of mean-field approximations to short-range correlated pair formation by showing that the relative abundance of short-range pairs in the nucleus is a long-range (that is, mean field) quantity that is insensitive to the short-distance nature of the nuclear force.Effects of nucleon–nucleon correlations are studied with the generalized contact formalism and ab initio quantum Monte Carlo calculations. For nuclei from deuteron to 40Ca, the many-body nuclear wave function is shown to factorize at short distances.
The extraction of neutrino mixing parameters from accelerator-based neutrino-oscillation experiments relies on proper modeling of neutrino-nucleus scattering processes using neutrino interaction ...event generators. Experimental tests of these generators are difficult due to the broad range of neutrino energies produced in accelerator-based beams and the low statistics of current experiments. Here we overcome these difficulties by exploiting the similarity of neutrino and electron interactions with nuclei to test neutrino event generators using high-precision inclusive electron-scattering data. To this end, we revised the electron-scattering mode of the genie event generator (e-genie) to include electron-nucleus bremsstrahlung radiation effects and to use, when relevant, the exact same physics models and model parameters, as the standard neutrino-scattering version. We also implemented new models for quasielastic (QE) scattering and meson exchange currents (MECs) based on the theory-inspired super scaling approach SuSAv2. Comparing the new e-genie predictions with inclusive electron-scattering data, we find an overall adequate description of the data in the QE- and MEC-dominated lower energy transfer regime, especially when using the SuSAv2 models. Higher energy transfer interactions, which are dominated by resonance production, are still not well modeled by e-genie.
Mechanisms of spin-flavor SU(6) symmetry breaking in quantum chromodynamics (QCD) are studied via an extraction of the free neutron structure function from a global analysis of deep inelastic ...scattering (DIS) data on the proton and on nuclei from A=2 (deuterium) to 208 (lead). Modification of the structure function of nucleons bound in atomic nuclei (known as the EMC effect) are consistently accounted for within the framework of a universal modification of nucleons in short-range correlated (SRC) pairs. Our extracted neutron-to-proton structure function ratio F_{2}^{n}/F_{2}^{p} becomes constant for x_{B}≥0.6, equaling 0.47±0.04 as x_{B}→1, in agreement with theoretical predictions of perturbative QCD and the Dyson-Schwinger equation, and in disagreement with predictions of the scalar diquark dominance model. We also predict F_{2}^{^{3}He}/F_{2}^{^{3}H}, recently measured, as yet unpublished, by the MARATHON Collaboration, the nuclear correction function that is needed to extract F_{2}^{n}/F_{2}^{p} from F_{2}^{^{3}He}/F_{2}^{^{3}H}, and the theoretical uncertainty associated with this extraction.
This Letter shows quantitatively that the magnitude of the EMC effect measured in electron deep inelastic scattering at intermediate x(B), 0.35≤x(B)≤0.7, is linearly related to the short range ...correlation (SRC) scale factor obtained from electron inclusive scattering at x(B)≥1. The observed phenomenological relationship is used to extract the ratio of the deuteron to the free pn pair cross sections and F(2)(n)/F(2)(p), the ratio of the free neutron to free proton structure functions. We speculate that the observed correlation is because both the EMC effect and SRC are dominated by the high virtuality (high momentum) nucleons in the nucleus.
•Depression and anxiety among psychiatric inpatients were negatively associated with richness, alpha diversity, and specific bacterial taxa.•Microbiota richness, alpha diversity, and bacterial taxa ...early in the hospitalization were associated with depression remission at discharge.•Coprococcus catus may be a significant contributor to the association between the gut microbiota and psychiatric functioning.•A large psychiatric sample from a controlled environment and accounting for confounding variables are clear strengths of the current study.
Emerging evidence implicates the gut microbiota in central nervous system functioning via its effects on inflammation, the hypothalamic-pituitary axis, and/or neurotransmission. Our understanding of the cellular underpinnings of the brain-gut relationship is based almost exclusively on animal models with some small-scale human studies. This study examined the relationship between the gut microbiota and psychiatric symptom severity and treatment response among inpatients with serious mental illness.
We collected data from adult inpatients (N = 111). Measures of diagnoses, suicide severity, trauma, depression, and anxiety were collected shortly after admission, while self-collected fecal swabs were collected early in the course of hospitalization and processed using 16S rRNA gene sequencing and whole genome shotgun sequencing methods.
Results indicate that depression and anxiety severity shortly after admission were negatively associated with bacterial richness and alpha diversity. Additional analyses revealed a number of bacterial taxa associated with depression and anxiety severity. Gut microbiota richness and alpha diversity early in the course of hospitalization was a significant predictor of depression remission at discharge.
This study is among the first to demonstrate a gut microbiota relationship with symptom severity among psychiatric inpatients as well as a relationship to remission of depression post-treatment. These findings are consistent with animal models and limited human studies as well as with the broader literature implicating inflammation in the pathophysiology of depression. These findings offer the foundation for further studies of novel therapeutic approaches to the treatment, prevention of, or recurrence of serious mental illness.
Gene amplification and sequencing have led to the discovery of new pathogens as agents of disease and have enabled us to better classify microorganisms from culture. Sequence-based identification of ...bacteria and fungi using culture is more objective and accurate than conventional methods, especially for classifying unusual microorganisms that are emerging pathogens in immunocompromised hosts. Although a powerful tool, the interpretation of sequence-based classification can be challenging as microbial taxonomy grows more complex, without known clinical correlatives. Additionally, broad-range gene polymerase chain reaction and sequencing have emerged as alternative, culture-independent methods for detecting pathogens from clinical material. The promise of this technique has remained strong, limited mainly by contamination and inadequate sensitivity issues. This review explains sequence-based microbial classification, with emphasis on relating the complex world of microbial taxonomy to a clinical context. Additionally, this review discusses a rational approach to broad-range bacterial polymerase chain reaction and gene sequencing when applied directly to clinical samples.
The Heavy Photon Search experiment took its first data in a 2015 engineering run using a 1.056 GeV, 50 nA electron beam provided by CEBAF at the Thomas Jefferson National Accelerator Facility, ...searching for a prompt, electroproduced dark photon with a mass between 19 and 81 MeV/c2. A search for a resonance in the e+e− invariant mass distribution, using 1.7 days (1170 nb−1) of data, showed no evidence of dark photon decays above the large QED background, confirming earlier searches and demonstrating the full functionality of the experiment. Upper limits on the square of the coupling of the dark photon to the standard model photon are set at the level of 6×10−6. Future runs with higher luminosity will explore new territory.
To establish the role of antiemetic therapy with neurokinin-1 (NK1) receptor antagonists (RAs) in nonanthracycline and cyclophosphamide (AC)-based moderately emetogenic chemotherapy (MEC) regimens, ...this study evaluated single-dose intravenous (i.v.) fosaprepitant for the prevention of chemotherapy-induced nausea and vomiting (CINV) associated with non-AC MEC.
In this international, phase III, double-blind trial, adult cancer subjects scheduled to receive ≥1 non-AC MEC on day 1 were randomized to a regimen comprising single-dose i.v. fosaprepitant 150 mg or placebo along with ondansetron and dexamethasone on day 1; control regimen recipients received ondansetron on days 2 and 3. Primary end points were the proportion of subjects achieving a complete response (CR; no vomiting and no use of rescue medication) in the delayed phase (25–120 h after MEC initiation) and safety. Secondary end points included CR in the overall and acute phases (0–120 and 0–24 h after MEC initiation, respectively) and no vomiting in the overall phase. Nausea and the Functional Living Index-Emesis were assessed as exploratory end points.
The fosaprepitant regimen improved CR significantly in the delayed (78.9% versus 68.5%; P < 0.001) and overall (77.1% versus 66.9%; P < 0.001) phases, but not in the acute phase (93.2% versus 91.0%; P = 0.184), versus control. In the overall phase, the proportion of subjects with no vomiting (82.7% versus 72.9%; P < 0.001) and no significant nausea (83.2% versus 77.9%; P = 0.030) was also significantly improved with the fosaprepitant regimen. The fosaprepitant regimen was generally well tolerated.
Single-dose fosaprepitant added to a 5-HT3 RA and dexamethasone was well tolerated and demonstrated superior control of CINV (primary end point achieved) associated with non-AC MEC. This is the first study to evaluate NK1 RA therapy as an i.v. formulation in a well-defined non-AC MEC population.
NCT01594749 (https://clinicaltrials.gov/ct2/show/NCT01594749).
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