A relativistic Glauber approach to polarization transfer in 4He(\vec{e},e'\vec{p})

Polarization-transfer components for 4He(\vec{e},e'\vec{p})3H are computed within the relativistic multiple-scattering Glauber approximation (RMSGA). The RMSGA framework adopts relativistic single-particle wave functions and electron-nucleon couplings. The predictions with free and various parametrizations for the medium-modified electromagnetic form factors are compared to the world data.Comment: 2 pages, 1 figure Proceedings of the Int. School on Nuclear Physics, 26th Course, Erice (Sicily), September 16th- 24th, 2004; To appear in Progress in Particle and Nuclear Physic

Extracting the Weinberg angle at intermediate energies

A recent experiment by the NuTeV collaboration resulted in a surprisingly high value for the weak mixing angle $\sin^2 \theta_W$. The Paschos-Wolfenstein relation, relating neutrino cross sections to the Weinberg angle, is of pivotal importance in the NuTeV analysis. In this work, we investigate the sensitivity of the Paschos-Wolfenstein relation to nuclear structure aspects at neutrino energies in the few GeV range. Neutrino-nucleus cross sections are calculated for $^{16}$O and $^{56}$Fe target nuclei within a relativistic quasi-elastic nucleon-knockout model.Comment: To appear in the proceedings of International School of Nuclear Physics: 27th Course: "Neutrinos in Cosmology, in Astro, Particle and Nuclear Physics", Erice, Sicily, Italy, 16-24 Sep 200

A Comparison of Induced Value and Home-Grown Value Experiments to Test for Hypothetical Bias in Contingent Valuation

This study tests the hypothesis that hypothetical bias may not be related to value elicitation; rather it may be a value formation problem. When participants are asked to indicate their willingness to pay for an induced value good, we find no evidence of hypothetical bias for three different commodity types (public good, private good, and publicly provided private good). However, when these same subjects are asked to value homegrown goods with no pre-assigned induced value using the same elicitation mechanism, hypothetical values are roughly double actual payments in all three cases. These results support the hypothesis that the process of forming values in a homegrown setting may be a key contributor to hypothetical bias.contingent valuation, hypothetical bias, experiments, induced values, home-grown values

Strangeness content of the nucleon in quasielastic neutrino-nucleus reactions

We present a systematic study of the sensitivity of quasielastic neutrino-nucleus cross sections at intermediate energies to the strange quark sea of the nucleon. To this end, we investigate the impact of the weak strangeness form factors on the ratio of proton-to-neutron knockout, the ratio of neutral-to-charged current cross sections, on the Paschos-Wolfenstein relation, and on the longitudinal helicity asymmetry. The influence of axial as well as vector strangeness effects is discussed. For the latter, we introduce strangeness parameters from various hadron models and from a recent fit to data from parity violating electron scattering. In our model, the nuclear target is described in terms of a relativistic mean-field approach. The effects of final-state interactions on the outgoing nucleon are quantified within a relativistic multiple-scattering Glauber approach. Our results are illustrated with cross sections for the scattering of 1 GeV neutrinos and antineutrinos off a $^{12}$C target. Folding with a proposed FINeSSE (anti)neutrino energy-distribution has no qualitative influence on the overall sensitivity of the cross-section ratios to strangeness mechanisms. We show that vector strangeness effects are large and strongly $Q^2$ dependent.Comment: 25 pages, 12 figures, submitted to Phys. Rev.

Helicity asymmetries in neutrino-nucleus interactions

We investigate the helicity properties of the ejectile in quasi-elastic neutrino-induced nucleon-knockout reactions and consider the 12C target as a test case. A formalism based on a relativistic mean-field model is adopted. The influence of final-state interactions is evaluated within a relativistic multiple-scattering Glauber approximation (RMSGA) model. Our calculations reveal that the helicity asymmetries A_l in A(\overline{\nu},\overline{\nu}'N) processes are extremely sensitive to strange-quark contributions to the weak vector form-factors. Thereby, nuclear corrections, such as final-state interactions and off-shell ambiguities in the electroweak current operators, are observed to be of marginal importance. This facilitates extracting strange-quark information from the helicity asymmetry A_l.Comment: 14 pages, 6 figures, 1 table submitted to PL

Relativistic models for quasi-elastic neutrino scattering

We present quasi-elastic neutrino-nucleus cross sections in the energy range from 150 MeV up to 5 GeV for the target nuclei 12C and 56Fe. A relativistic description of the nuclear dynamics and the neutrino-nucleus coupling is adopted. For the treatment of final-state interactions (FSI) we rely on two frameworks succesfully applied to exclusive electron-nucleus scattering: a relativistic optical potential and a relativistic multiple-scattering Glauber approximation. At lower energies, the optical-potential approach is considered to be the optimum choice, whereas at high energies a Glauber approach is more natural. Comparing the results of both calculations, it is found that the Glauber approach yields valid results down to the remarkably small nucleon kinetic energies of 200 MeV. We argue that the nuclear transparencies extracted from A(e,e'p) measurements can be used to obtain realistic estimates of the effect of FSI mechanisms on quasi-elastic neutrino-nucleus cross sections. We present two independent relativistic plane-wave impulse approximation (RPWIA) calculations of quasi-elastic neutrino-nucleus cross sections. They agree at the percent level, showing the reliability of the numerical techniques adopted and providing benchmark RPWIA results.Comment: revised version,28 pages, 7 figures, accepted in Phys.Rev.

Relativistic eikonal description of A(p,pN) reactions

The authors present a relativistic and cross-section factorized framework for computing quasielastic A(p,pN) observables at intermediate and high energies. The model is based on the eikonal approximation and can accomodate both optical potentials and the Glauber method for dealing with the initial- and final-state interactions (IFSI). At lower nucleon energies, the optical-potential philosophy is preferred, whereas at higher energies the Glauber method is more natural. This versatility in dealing with the IFSI allows one to describe A(p,pN) reactions in a wide energy range. Most results presented here use optical potentials as this approach is argued to be the optimum choice for the kinematics of the experiments considered in the present paper. The properties of the IFSI factor, a function wherein the entire effect of the IFSI is contained, are studied in detail. The predictions of the presented framework are compared with two kinematically different experiments. First, differential cross sections for quasielastic proton scattering at 1 GeV off 12C, 16O, and 40Ca target nuclei are computed and compared to data from PNPI. Second, the formalism is applied to the analysis of a 4He(p,2p) experiment at 250 MeV. The optical-potential calculations are found to be in good agreement with the data from both experiments, showing the reliability of the adopted model in a wide energy range.Comment: 34 pages, 14 figures, accepted for publication in Phys. Rev.

The underlying challenges that arise when analysing short-chain chlorinated paraffins in environmental matrices

As short-chain chlorinated paraffins (SCCPs) are listed on several monitoring programs, validated methods are essential. However, their complexity and the lack of commercially available certified reference materials (RMs) hinder a proper validation of methods. Instead, one method is usually ‘validated’ by evaluating performances and results of spiked materials with that of one other method, which could easily lead to unreliable results. This study evaluated four analytical methods with different principles (i.e. comprehensive two dimensional GC coupled to a micro electron capture detector, developed for this study, chloride enhanced atmospheric pressure chemical ionization triple quadrupole time of flight MS (APCI-QToF-HRMS), GC coupled to an electron capture negative ion low resolution MS (GC–ECNI–LRMS) and carbon skeleton GC–MS), investigated the comparability in SCCP determination in spiked and naturally contaminated samples and determined SCCP amounts in candidate RMs for possible certification. The results cast doubt on the use of the most commonly applied method (i.e. GC–ECNI–LRMS), as well as using spiked materials for method validation. The APCI-QToF-HRMS method was found most promising as it achieves the required MS resolution (>21,000), is relatively fast and can detect also other CPs. The suitable identified SCCP levels in the candidate RMs and the agreement in results between the methods bring the first certification of a RM for SCCPs within reach

Increased Trauma Activation Is Not Equally Beneficial For All Elderly Trauma Patients

Background Physiologic changes in the elderly lead to higher morbidity and mortality after injury. Increasing level of trauma activation has been proposed to improve geriatric outcomes; but, the increased cost to the patient and stress to the hospital system are significant downsides. The purpose of this study was to identify the age at which an increase in activation status is beneficial. Methods A retrospective review of trauma patients ≥ 70 years old from October 1, 2011, to October 1, 2016 was performed. On October 1, 2013, a policy change increased the activation criteria to the highest level for patients ≥ 70 years of age with a significant mechanism of injury. Patients who presented prior to (PRE) were compared to those after the change (POST). Data collected included age, injury severity score (ISS), length of stay (LOS), complications and mortality. Primary outcome was mortality and secondary outcome was LOS. Multivariable regressions controlled for age, ISS, injury mechanism, and number of complications. Results 4341 patients met inclusion criteria, 1919 in PRE and 2422 in POST. Mean age was 80.4 and 81 years in PRE and POST groups respectively (p=0.0155). Mean ISS values were 11.6 and 12.4 (p<0.0001) for the PRE and POST groups. POST had more level 1 activations (696 vs. 220, p<0.0001). After controlling for age, ISS, mechanism of injury, and number of complications, mortality was significantly reduced in the POST group ≥ age 77 years (OR 0.53, 95% CI: 0.3 - 0.87), (Figure 1). Hospital LOS was significantly reduced in the POST group ≥ age 78 (regression coefficient -0.55, 95% CI: -1.09, -0.01) (Figure 2). Conclusions This study suggests geriatric trauma patients ≥ 77 years benefit from the highest level of trauma activation with shorter LOS and lower mortality. A focused approach to increasing activation level for elderly patients may decrease patient cost. Level of Evidence Level III Type of Study Economic/Decisio

To Sleep, Perchance to Dream: Acute and Chronic Sleep Deprivation in Acute Care Surgeons

Background Acute and chronic sleep deprivation are significantly associated with depressive symptoms and felt to be contributors to the development of burnout. In-house call (IHC) inherently includes frequent periods of disrupted sleep and is common amongst acute care surgeons (ACS). The relationship between IHC and sleep deprivation (SD) amongst ACS has not been previously studied. The goal of this study was to determine prevalence and patterns of SD in ACS. Study Design: A prospective study of ACS with IHC responsibilities from two Level I trauma centers was performed. Participants wore a sleep tracking device continuously over a 3-month period. Data collected included age, gender, schedule of IHC, hours and pattern of each sleep stage (light, slow wave (SWS), and REM), and total hours of sleep. Sleep patterns were analyzed for each night excluding IHC and categorized as normal (N), acute sleep deprivation (ASD), or chronic sleep deprivation (CSD). Results 1421 nights were recorded amongst 17 ACS. (35.3% female; ages 37-65, mean 45.5 years). Excluding IHC, average amount of sleep was 6.54 hours with 64.8% of sleep patterns categorized as ASD or CSD. Average amount of sleep was significantly higher on post-call day 1 (6.96 hours, p=0.0016), but decreased significantly on post-call day 2 (6.33 hours, p=0.0006). Sleep patterns with ASD and CSD peaked on post-call day 2, and returned to baseline on post-call day 3 (p=0.046). Conclusion Sleep patterns consistent with ASD and CSD are common amongst ACS and worsen on post-call day 2. Baseline sleep patterns were not recovered until post-call day 3. Future study is needed to identify factors which impact physiologic recovery after IHC and further elucidate the relationship between SD and burnout