Precision Determination of the Neutral Weak Form Factor of ^{48}Ca

We report a precise measurement of the parity-violating (PV) asymmetry A_{PV} in the elastic scattering of longitudinally polarized electrons from ^{48}Ca. We measure A_{PV}=2668±106(stat)±40(syst) parts per billion, leading to an extraction of the neutral weak form factor F_{W}(q=0.8733  fm^{-1})=0.1304±0.0052(stat)±0.0020(syst) and the charge minus the weak form factor F_{ch}-F_{W}=0.0277±0.0055. The resulting neutron skin thickness R_{n}-R_{p}=0.121±0.026(exp)±0.024(model)  fm is relatively thin yet consistent with many model calculations. The combined CREX and PREX results will have implications for future energy density functional calculations and on the density dependence of the symmetry energy of nuclear matter.

Deeply Virtual Compton Scattering Cross Section at High Bjorken x_{B}

We report high-precision measurements of the deeply virtual Compton scattering (DVCS) cross section at high values of the Bjorken variable x_{B}. DVCS is sensitive to the generalized parton distributions of the nucleon, which provide a three-dimensional description of its internal constituents. Using the exact analytic expression of the DVCS cross section for all possible polarization states of the initial and final electron and nucleon, and final state photon, we present the first experimental extraction of all four helicity-conserving Compton form factors (CFFs) of the nucleon as a function of x_{B}, while systematically including helicity flip amplitudes. In particular, the high accuracy of the present data demonstrates sensitivity to some very poorly known CFFs.

New Measurements of the Beam-Normal Single Spin Asymmetry in Elastic Electron Scattering over a Range of Spin-0 Nuclei

We report precision determinations of the beam-normal single spin asymmetries (A_{n}) in the elastic scattering of 0.95 and 2.18 GeV electrons off ^{12}C, ^{40}Ca, ^{48}Ca, and ^{208}Pb at very forward angles where the most detailed theoretical calculations have been performed. The first measurements of A_{n} for ^{40}Ca and ^{48}Ca are found to be similar to that of ^{12}C, consistent with expectations and thus demonstrating the validity of theoretical calculations for nuclei with Z≤20. We also report A_{n} for ^{208}Pb at two new momentum transfers (Q^{2}) extending the previous measurement. Our new data confirm the surprising result previously reported, with all three data points showing significant disagreement with the results from the Z≤20 nuclei. These data confirm our basic understanding of the underlying dynamics that govern A_{n} for nuclei containing ≲50 nucleons, but point to the need for further investigation to understand the unusual A_{n} behavior discovered for scattering off ^{208}Pb.

Measurement of the Nucleon F_{2}^{n}/F_{2}^{p} Structure Function Ratio by the Jefferson Lab MARATHON Tritium/Helium-3 Deep Inelastic Scattering Experiment

The ratio of the nucleon F_{2} structure functions, F_{2}^{n}/F_{2}^{p}, is determined by the MARATHON experiment from measurements of deep inelastic scattering of electrons from ^{3}H and ^{3}He nuclei. The experiment was performed in the Hall A Facility of Jefferson Lab using two high-resolution spectrometers for electron detection, and a cryogenic target system which included a low-activity tritium cell. The data analysis used a novel technique exploiting the mirror symmetry of the two nuclei, which essentially eliminates many theoretical uncertainties in the extraction of the ratio. The results, which cover the Bjorken scaling variable range 0.19<x<0.83, represent a significant improvement compared to previous SLAC and Jefferson Lab measurements for the ratio. They are compared to recent theoretical calculations and empirical determinations of the F_{2}^{n}/F_{2}^{p} ratio.

Determination of the ^{27}Al Neutron Distribution Radius from a Parity-Violating Electron Scattering Measurement

We report the first measurement of the parity-violating elastic electron scattering asymmetry on ^{27}Al. The ^{27}Al elastic asymmetry is A_{PV}=2.16±0.11(stat)±0.16(syst)  ppm, and was measured at ⟨Q^{2}⟩=0.02357±0.00010  GeV^{2}, ⟨θ_{lab}⟩=7.61°±0.02°, and ⟨E_{lab}⟩=1.157  GeV with the Q_{weak} apparatus at Jefferson Lab. Predictions using a simple Born approximation as well as more sophisticated distorted-wave calculations are in good agreement with this result. From this asymmetry the ^{27}Al neutron radius R_{n}=2.89±0.12  fm was determined using a many-models correlation technique. The corresponding neutron skin thickness R_{n}-R_{p}=-0.04±0.12  fm is small, as expected for a light nucleus with a neutron excess of only 1. This result thus serves as a successful benchmark for electroweak determinations of neutron radii on heavier nuclei. A tree-level approach was used to extract the ^{27}Al weak radius R_{w}=3.00±0.15  fm, and the weak skin thickness R_{wk}-R_{ch}=-0.04±0.15  fm. The weak form factor at this Q^{2} is F_{wk}=0.39±0.04.

Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering

We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q^{2}) up to 15.75  (GeV/c)^{2}. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q^{2} and double the range over which a longitudinal or transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q^{2} and attributed to hard two-photon exchange (TPE) effects, extending to 8  (GeV/c)^{2} the range of Q^{2} for which a discrepancy is established at >95% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q^{2}.

Deep Exclusive Electroproduction of π^{0} at High Q^{2} in the Quark Valence Regime

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of x_{B} (0.36, 0.48, and 0.60) and Q^{2} (3.1 to 8.4  GeV^{2}) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions dσ_{T}/dt+εdσ_{L}/dt, dσ_{TT}/dt, dσ_{LT}/dt, and dσ_{LT^{'}}/dt are extracted as a function of the proton momentum transfer t-t_{min}. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross section throughout this kinematic range. The data are well described by calculations based on transversity generalized parton distributions coupled to a helicity flip distribution amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.

Enhancements in laser-generated hot-electron production via focusing cone targets at short pulse and high contrast

We report on the increase in the accelerated electron number and energy using compound parabolic concentrator (CPC) targets from a short-pulse (∼150 fs), high-intensity (>10^{18} W/cm^{2}), and high-contrast (∼10^{8}) laser-solid interaction. We report on experimental measurements using CPC targets where the hot-electron temperature is enhanced up to ∼9 times when compared to planar targets. The temperature measured from the CPC target is 〈T_{e}〉=4.4±1.3 MeV. Using hydrodynamic and particle in cell simulations, we identify the primary source of this temperature enhancement is the intensity increase caused by the CPC geometry that focuses the laser, reducing the focal spot and therefore increasing the intensity of the laser-solid interaction, which is also consistent with analytic expectations for the geometrical focusing.

Accurate Determination of the Neutron Skin Thickness of ^{208}Pb through Parity-Violation in Electron Scattering

We report a precision measurement of the parity-violating asymmetry A_{PV} in the elastic scattering of longitudinally polarized electrons from ^{208}Pb. We measure A_{PV}=550±16(stat)±8(syst) parts per billion, leading to an extraction of the neutral weak form factor F_{W}(Q^{2}=0.00616  GeV^{2})=0.368±0.013. Combined with our previous measurement, the extracted neutron skin thickness is R_{n}-R_{p}=0.283±0.071  fm. The result also yields the first significant direct measurement of the interior weak density of ^{208}Pb: ρ_{W}^{0}=-0.0796±0.0036(exp)±0.0013(theo)  fm^{-3} leading to the interior baryon density ρ_{b}^{0}=0.1480±0.0036(exp)±0.0013(theo)  fm^{-3}. The measurement accurately constrains the density dependence of the symmetry energy of nuclear matter near saturation density, with implications for the size and composition of neutron stars.

Microcoulomb (0.7 ± [Formula: see text] μC) laser plasma accelerator on OMEGA EP

Laser-plasma accelerators (LPAs) driven by picosecond-scale, kilojoule-class lasers can generate particle beams and x-ray sources that could be utilized in experiments driven by multi-kilojoule, high-energy-density science (HEDS) drivers such as the OMEGA laser at the Laboratory for Laser Energetics (LLE) or the National Ignition Facility at Lawrence Livermore National Laboratory. This paper reports on the development of the first LPA driven by a short-pulse, kilojoule-class laser (OMEGA EP) connected to a multi-kilojoule HEDS driver (OMEGA). In experiments, electron beams were produced with electron energies greater than 200 MeV, divergences as low as 32 mrad, charge greater than 700 nC, and conversion efficiencies from laser energy to electron energy up to 11%. The electron beam charge scales with both the normalized vector potential and plasma density. These electron beams show promise as a method to generate MeV-class radiography sources and improved-flux broadband x-ray sources at HEDS drivers.

Ruling out Color Transparency in Quasielastic ^{12}C(e,e^{'}p) up to Q^{2} of 14.2 (GeV/c)^{2}

Quasielastic ^{12}C(e,e^{'}p) scattering was measured at spacelike 4-momentum transfer squared Q^{2}=8, 9.4, 11.4, and 14.2  (GeV/c)^{2}, the highest ever achieved to date. Nuclear transparency for this reaction was extracted by comparing the measured yield to that expected from a plane-wave impulse approximation calculation without any final state interactions. The measured transparency was consistent with no Q^{2} dependence, up to proton momenta of 8.5  GeV/c, ruling out the quantum chromodynamics effect of color transparency at the measured Q^{2} scales in exclusive (e,e^{'}p) reactions. These results impose strict constraints on models of color transparency for protons.

Precision Measurement of the Beam-Normal Single-Spin Asymmetry in Forward-Angle Elastic Electron-Proton Scattering

A beam-normal single-spin asymmetry generated in the scattering of transversely polarized electrons from unpolarized nucleons is an observable related to the imaginary part of the two-photon exchange process. We report a 2% precision measurement of the beam-normal single-spin asymmetry in elastic electron-proton scattering with a mean scattering angle of θ_{lab}=7.9° and a mean energy of 1.149 GeV. The asymmetry result is B_{n}=-5.194±0.067(stat)±0.082 (syst) ppm. This is the most precise measurement of this quantity available to date and therefore provides a stringent test of two-photon exchange models at far-forward scattering angles (θ_{lab}→0) where they should be most reliable.

Unique Access to u-Channel Physics: Exclusive Backward-Angle Omega Meson Electroproduction

Backward-angle meson electroproduction above the resonance region, which was previously ignored, is anticipated to offer unique access to the three quark plus sea component of the nucleon wave function. In this Letter, we present the first complete separation of the four electromagnetic structure functions above the resonance region in exclusive ω electroproduction off the proton, ep→e^{'}pω, at central Q^{2} values of 1.60, 2.45  GeV^{2}, at W=2.21  GeV. The results of our pioneering -u≈-u_{min} study demonstrate the existence of a unanticipated backward-angle cross section peak and the feasibility of full L/T/LT/TT separations in this never explored kinematic territory. At Q^{2}=2.45  GeV^{2}, the observed dominance of σ_{T} over σ_{L}, is qualitatively consistent with the collinear QCD description in the near-backward regime, in which the scattering amplitude factorizes into a hard subprocess amplitude and baryon to meson transition distribution amplitudes: universal nonperturbative objects only accessible through backward-angle kinematics.

X-ray analysis methods for sources from self-modulated laser wakefield acceleration driven by picosecond lasers

A versatile set of methods for analyzing x-ray energy spectra and photon flux has been developed for laser plasma accelerator experiments driven by picosecond lasers. Forward fit provides extrapolated broad energy spectrum measurements, while Ross pair and differential average transmission analysis provide directly measured data points using a particular diagnostic. Combining these methods allows the measurement of x-ray energy spectra with improved confidence. We apply the methods to three diagnostics (filter wheel, stacked image plate spectrometer, and step wedge), each sensitive to a different region of x-ray energies (<40 keV, 35-100 keV, and 60-1000 keV, respectively), to characterize the analysis methods using laser-driven bremsstrahlung x-rays. We then apply the methods to measure three x-ray mechanisms, betatron, inverse Compton scattering, and bremsstrahlung, driven by a laser plasma accelerator. The analysis results in the measurement of x-ray energy spectra ranging from 10 keV to 1 MeV with peak flux greater than 10¹⁰ photons/keV/Sr. The combined analysis methods provide a robust tool to accurately measure broadband x-ray sources (keV to MeV) driven by laser plasma acceleration with picosecond, kilojoule-class lasers.

Revealing Color Forces with Transverse Polarized Electron Scattering

The Spin Asymmetries of the Nucleon Experiment measured two double spin asymmetries using a polarized proton target and polarized electron beam at two beam energies, 4.7 and 5.9 GeV. A large-acceptance open-configuration detector package identified scattered electrons at 40° and covered a wide range in Bjorken x (0.3<x<0.8). Proportional to an average color Lorentz force, the twist-3 matrix element, d[over ˜]_{2}^{p}, was extracted from the measured asymmetries at Q^{2} values ranging from 2.0 to 6.0  GeV^{2}. The data display the opposite sign compared to most quark models, including the lattice QCD result, and an unexpected scale dependence. Furthermore, when combined with the neutron data in the same Q^{2} range the results suggest a flavor independent average color Lorentz force.

Separated response function ratios in exclusive, forward π(±) electroproduction

The study of exclusive π(±) electroproduction on the nucleon, including separation of the various structure functions, is of interest for a number of reasons. The ratio RL=σL(π-)/σL(π+) is sensitive to isoscalar contamination to the dominant isovector pion exchange amplitude, which is the basis for the determination of the charged pion form factor from electroproduction data. A change in the value of RT=σT(π-)/σT(π+) from unity at small -t, to 1/4 at large -t, would suggest a transition from coupling to a (virtual) pion to coupling to individual quarks. Furthermore, the mentioned ratios may show an earlier approach to perturbative QCD than the individual cross sections. We have performed the first complete separation of the four unpolarized electromagnetic structure functions above the dominant resonances in forward, exclusive π(±) electroproduction on the deuteron at central Q(2) values of 0.6, 1.0, 1.6  GeV(2) at W=1.95  GeV, and Q(2)=2.45  GeV(2) at W=2.22  GeV. Here, we present the L and T cross sections, with emphasis on RL and RT, and compare them with theoretical calculations. Results for the separated ratio RL indicate dominance of the pion-pole diagram at low -t, while results for RT are consistent with a transition between pion knockout and quark knockout mechanisms.

The ergonomics of child care: conducting worksite analyses

This paper examined the ergonomics of child care at a large metropolitan, university-based child care center. A case study approach was used to describe the job analysis process and results. Center staff were involved in the identification of health risk factors by completing an ergonomics survey and responding to questions posed during the job analysis (n=36). Two occupational therapists analyzed six different rooms, accommodating different age groups of children. Specific activities were identified as stressors and/or health risk factors inherent in the jobs according to the age of the children cared for. A list of ergonomic health risk factors and recommendations was generated.

Abstract P1-01-11: The health economics of one step nucleic acid amplification for intraoperative sentinel lymph node analysis in breast cancer

AIM

Despite the obvious advantages of intraoperative sentinel lymph node (SLN) analysis in the form of One Step Nucleic Acid Amplification (OSNA), this technique has not been widely adopted in the United Kingdom. The aim of this study was to investigate the health economic implication of the technique.

METHODS

Data were collected prospectively on all patients undergoing OSNA at a single institution between September 2011 and February 2013. Initially patients were selected using the Sloan Kettering Nomogram for additional non SLN axillary disease [http://nomograms.mskcc.org] and patients with micrometastases were offered an axillary clearance. From August 2012, all patients undergoing sentinel node biopsy were offered OSNA. A cost analysis was done on the basis of up front purchase costs, OSNA cost per patient minus the cost of standard Haematoxylin and Eosin stain analyses at our institution and HRG4 codes.

RESULTS

Data were collected on 258 patients with a median age of 69. 209 (81%) had invasive ductal carcinoma. 208(80%) were oestrogen receptor positive and approximately 30% had lymphovascular invasion. Table 2 demonstrates the OSNA results.

Table 1 - OSNA results Pre August 2012Post August 2012Total n%n%n%No. of patients169 88 257 Mean no. of nodes2.38 1.98 2.24 OSNA Negative11668.645461.3617066.15OSNA Micrometastases2715.982123.864818.68OSNA Macrometastases2112.431314.773413.23OSNA Inhibited52.960051.95Total no. undergoing Axillary Clearance5130.181820.456926.85Axillary Clearance for Micrometastases2313.6144.552710.51Additional nodes positive overall:      03772.55950.004666.671-3 nodes1121.57738.891826.094-7 nodes11.96211.1134.358-12 nodes11.96  11.45gt]12 nodes[11.96  11.45Additional nodes positive for OSNA Micrometastases:      021  22385.191-3 nodes2   414.81

The capital investment for setting up OSNA in our institution was £40,000. By carrying out OSNA on all patients undergoing sentinel node biopsy we saved a second procedure on 20% of patients. Table 2 outlines the costs saving per year based on the HRG4 code for the cost of second admission and axillary clearance.

Table 2 - Health Economic Analysis  TotalNo. patients undergoing OSNA per year235 Cost of OSNA per patient£286£67,210Cost of H & E analysis based on 2 nodes per patient£101,60£23,876Net costs of OSNA per patient£184,40£43,334No. patients undergoing axillary clearance (20% of 235)47 Cost of axillary clearance (based on HRG4 JA07)£2,030£95,410Total saving per year with OSNA £52,076

CONCLUSION

The use of OSNA as an intraoperative assessment of sentinel lymph nodes in breast cancer is a highly sensitive and efficient way of determining the sentinel node status. It saves patients undergoing a second admission and procedure. By offering OSNA to all patients undergoing SLN, the capital investment will be recouped in less than a year and the local health economy will save over £50,000 per year in subsequent years.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-01-11.

First determination of the weak charge of the proton

The Q(weak) experiment has measured the parity-violating asymmetry in ep elastic scattering at Q(2)=0.025(GeV/c)(2), employing 145 μA of 89% longitudinally polarized electrons on a 34.4 cm long liquid hydrogen target at Jefferson Lab. The results of the experiment's commissioning run, constituting approximately 4% of the data collected in the experiment, are reported here. From these initial results, the measured asymmetry is A(ep)=-279±35 (stat) ± 31 (syst) ppb, which is the smallest and most precise asymmetry ever measured in ep scattering. The small Q(2) of this experiment has made possible the first determination of the weak charge of the proton Q(W)(p) by incorporating earlier parity-violating electron scattering (PVES) data at higher Q(2) to constrain hadronic corrections. The value of Q(W)(p) obtained in this way is Q(W)(p)(PVES)=0.064±0.012, which is in good agreement with the standard model prediction of Q(W)(p)(SM)=0.0710±0.0007. When this result is further combined with the Cs atomic parity violation (APV) measurement, significant constraints on the weak charges of the up and down quarks can also be extracted. That PVES+APV analysis reveals the neutron's weak charge to be Q(W)(n)(PVES+APV)=-0.975±0.010.

Measurement of the neutron F2 structure function via spectator tagging with CLAS

We report on the first measurement of the F(2) structure function of the neutron from the semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to ≲100 MeV/c and their angles to ≳100° relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F(2)(n) data collected cover the nucleon-resonance and deep-inelastic regions over a wide range of Bjorken x for 0.65<Q(2)<4.52 GeV(2), with uncertainties from nuclear corrections estimated to be less than a few percent. These measurements provide the first determination of the neutron to proton structure function ratio F(2)(n)/F(2)(p) at 0.2≲x≲0.8 with little uncertainty due to nuclear effects.

Measurement of the parity-violating asymmetry in inclusive electroproduction of π- near the Δ0 resonance

The parity-violating (PV) asymmetry of inclusive π- production in electron scattering from a liquid deuterium target was measured at backward angles. The measurement was conducted as a part of the G0 experiment, at a beam energy of 360 MeV. The physics process dominating pion production for these kinematics is quasifree photoproduction off the neutron via the Δ0 resonance. In the context of heavy-baryon chiral perturbation theory, this asymmetry is related to a low-energy constant d(Δ)- that characterizes the parity-violating γNΔ coupling. Zhu et al. calculated d(Δ)- in a model benchmarked by the large asymmetries seen in hyperon weak radiative decays, and predicted potentially large asymmetries for this process, ranging from A(γ)-=-5.2 to +5.2  ppm. The measurement performed in this work leads to A(γ)-=-0.36±1.06±0.37±0.03  ppm (where sources of statistical, systematic and theoretical uncertainties are included), which would disfavor enchancements considered by Zhu et al. proportional to V(ud)/V(us). The measurement is part of a program of inelastic scattering measurements that were conducted by the G0 experiment, seeking to determine the N-Δ axial transition form factors using PV electron scattering.

Measurement of the neutron radius of 208Pb through parity violation in electron scattering

We report the first measurement of the parity-violating asymmetry A(PV) in the elastic scattering of polarized electrons from 208Pb. A(PV) is sensitive to the radius of the neutron distribution (R(n)). The result A(PV)=0.656±0.060(stat)±0.014(syst) ppm corresponds to a difference between the radii of the neutron and proton distributions R(n)-R(p)=0.33(-0.18)(+0.16) fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus.

Transverse beam spin asymmetries at backward angles in elastic electron-proton and quasielastic electron-deuteron scattering

We have measured the beam-normal single-spin asymmetries in elastic scattering of transversely polarized electrons from the proton, and performed the first measurement in quasielastic scattering on the deuteron, at backward angles (lab scattering angle of 108°) for Q² = 0.22 GeV²/c² and 0.63 GeV²/c² at beam energies of 362 and 687 MeV, respectively. The asymmetry arises due to the imaginary part of the interference of the two-photon exchange amplitude with that of single-photon exchange. Results for the proton are consistent with a model calculation which includes inelastic intermediate hadronic (πN) states. An estimate of the beam-normal single-spin asymmetry for the scattering from the neutron is made using a quasistatic deuterium approximation, and is also in agreement with theory.

A qualitative evaluation of patients' experiences of an enhanced recovery programme for colorectal cancer

AIM

We explored the patients' views and experiences of surgery for colorectal cancer within an enhanced recovery programme (ERP).

METHOD

Semi-structured home interviews were performed within 6 weeks of hospital discharge with participants of a randomized trial comparing laparoscopically assisted surgery with open surgery for colorectal cancer within an ERP. Interviews were tape-recorded, transcribed and analysed using qualitative techniques of constant comparison based upon grounded theory.

RESULTS

Interviewees (n = 22) had similar baseline characteristics and clinical outcomes to participants in the full trial. Many participants were pleased to be discharged quickly and they considered that being in their own home-improved recovery because it allowed them to choose how and when to undertake daily activities rather than following the hospital routine. Some participants (n = 9) were less satisfied with the process, and the reasons for this were related to complications requiring readmission or needing to contact a health professional for information after discharge.

CONCLUSION

Although many participants reported benefits from an ERP, the study highlighted areas for improvement. In particular participants reported the need for better access to information and specialist advice in the early days after hospital discharge.

Strange quark contributions to parity-violating asymmetries in the backward angle G0 electron scattering experiment

We have measured parity-violating asymmetries in elastic electron-proton and quasielastic electron-deuteron scattering at Q2=0.22 and 0.63 GeV2. They are sensitive to strange quark contributions to currents in the nucleon and the nucleon axial-vector current. The results indicate strange quark contributions of approximately < 10% of the charge and magnetic nucleon form factors at these four-momentum transfers. We also present the first measurement of anapole moment effects in the axial-vector current at these four-momentum transfers.

Detailed evaluation of functional recovery following laparoscopic or open surgery for colorectal cancer within an enhanced recovery programme

BACKGROUND AND AIMS

Evidence demonstrating improved short-term outcomes with laparoscopic surgery compared with open surgery for colorectal cancer is accumulating. In addition, programmes optimising peri-operative care for major abdominal surgery are becoming widespread. Evaluating laparoscopic surgery and enhanced recovery programmes usually focuses on short-term recovery. The aim of this study was to compare recovery after laparoscopic and open surgery for colorectal cancer up to 1 year post-operatively, using a combination of self-report and observer data.

PATIENTS/METHODS

From January 2002 to March 2004, 62 patients were randomised (2:1) to receive laparoscopic (n=43) or open surgery (n=19) within an enhanced recovery programme. Functional outcomes up to 1 year were assessed using interview-administered questionnaires.

RESULTS/FINDINGS

Questionnaire and health-related quality of life data were obtained in over 85% of patients. Patients undergoing laparoscopic surgery felt fully recovered and resumed driving more quickly than those having open surgery (p=0.016 and p=0.048 respectively). Fifty-eight percent of patients having open surgery felt fully recovered by 12 months versus 88% of laparoscopic patients.

INTERPRETATION/CONCLUSION

Within an enhanced recovery programme, patients undergoing laparoscopic surgery recovered more quickly than after open resection. Both approaches however, were associated with slow recovery despite a relatively short hospital stay.

The accuracy of clinical data: a comparison between central and local data collection

BACKGROUND

The recent liberalisation of public access to information, including surgical performance, emphasises the necessity for accurate data collection. The Information and Statistics Division of the Scottish Executive (ISD) collect such data for each patient episode, but there is concern about the reliability of this information compared with that collected in local surgical departmental audit.

AIM

To determine if diagnostic and operative details were consistent between local audited and national non-audited data sets.

METHODS

Three surgical units comprising eight consultants were studied. Epidemiological, diagnostic and operative data for each consultant were accessed from the eScrips Internet resource (ISD Data) and from the departmental database. A unique patient number and date of birth matched individual patient episodes and the correlation between datasets graded for accuracy and consistency.

RESULTS

8375 individual data entries were recorded (ISD 4642, local databases 3733). 3402 pairs, 6408 (76.5%) of the total, matched accurately. 742 (16%) of the ISD entries were duplicates, and in 21% of unpaired entries the wrong consultant was recorded. Overall a clinically acceptable match occurred in 86.9% of paired entries for diagnosis and 84.0% for operation. The highest match with ISD data for diagnosis (88.8%) and operation (91.8%) occurred in the unit which holds a weekly audit meeting to validate information.

DISCUSSION

There are significant discrepancies in surgical data between the local audit databases and central data. There is significant duplication of entries and inaccurate consultant allocation in ISD data. The promulgation of inaccurate information could threaten reputation or career and clinicians should play a more active role in ensuring clinical data are correct.

Healing by primary versus secondary intention after surgical treatment for pilonidal sinus

BACKGROUND

Pilonidal sinus arises in the hair follicles in the buttock cleft at the bottom of the backbone. The estimated incidence is 26 per 100,000, people, affecting men twice as often as women. The mean age of presentation is 21 years (men) and 19 years (women) respectively.Pilonidal sinus results in chronic discharging wounds that cause pain and impact upon quality of life and social function. These sinuses may become infected and present as acute abscesses. Management of these abscesses is uncontroversial and revolves around incision and drainage, however, the mode of surgical management of the chronic discharging sinus is debatable. Surgical strategies traditionally centre on excision of the sinus tracts followed by primary closure and healing by primary intention or leaving the wound open to heal by secondary intention. There is uncertainty as to whether open or closed surgical management is more effective.

OBJECTIVES

To determine the relative effects of open compared with closed surgical treatment for pilonidal sinus on the outcomes of time to healing, infection and recurrence rate.

SEARCH STRATEGY

We sought relevant trials from the Wounds Group Specialised Register (Searched 13/6/07); The Cochrane Central Register of Controlled Trials (CENTRAL) (2007, Issue 2); Ovid MEDLINE (1950 - May Week 5 200& ); Ovid EMBASE (1980 - 2007 Week 23); Ovid CINAHL (1982 - June Week 2 2007). We checked the bibliographies of review and primary articles for relevant studies and contacted authors of all included studies.

SELECTION CRITERIA

All randomised controlled trials (RCTs) evaluating open with closed surgical treatment for pilonidal sinus. Exclusion criteria were: non-RCTs; children aged younger than 14 years and studies of pilonidal abscess.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, data extraction and methodological quality assessment of trials were conducted independently by two review authors. Data from eligible studies were recorded using data extraction forms and any disagreements were referred to a third review author. Results were presented using mean differences for continuous outcomes and relative risk with 95% confidence intervals for dichotomous outcomes.

MAIN RESULTS

Eighteen studies were included (1573 patients). Twelve RCTs compared open healing with primary closure, 10 of which used midline closure and 2 trials used off-midline closure. Six studies compared midline and off-midline closure. Open compared with closed techniques: Evidence suggested more rapid healing after primary closure although there was no difference in the infection rate after wound closure. Recurrence was less likely to occur after open healing (RR 0.42; 95% CI 0.26 to 0.66) suggesting a 58% lower risk of recurrence after open wound healing compared with primary closure. Patients returned to work earlier after primary closure (WMD 10.48 days 95% CI 5.75 to 15.21 days). There was no difference between the two groups for other complications and length of stay. There were few useable data on cost, patient satisfaction and pain. Closed midline compared with closed off-midline: there was good evidence of slower healing, higher rates of infection (RR 4.70; 95% CI 1.93 to 11.45), higher rates of recurrence (Peto OR 4.95; 95% CI 2.18 to 11.24) and other complications (RR 8.94; 95% CI 2.10 to 38.02) after midline primary closure compared with off-midline closure techniques.

AUTHORS' CONCLUSIONS

No clear benefit was shown for surgical management by primary closure or open healing by secondary intention. A clear benefit was shown for off-midline closure rather than midline closure after pilonidal sinus surgery. Off-midline closure should be the standard management when primary closure is the desired surgical option.

Transverse beam spin asymmetries in forward-angle elastic electron-proton scattering

We have measured the beam-normal single-spin asymmetry in elastic scattering of transversely polarized 3 GeV electrons from unpolarized protons at Q2=0.15, 0.25 (GeV/c)2. The results are inconsistent with calculations solely using the elastic nucleon intermediate state and generally agree with calculations with significant inelastic hadronic intermediate state contributions. A(n) provides a direct probe of the imaginary component of the 2gamma exchange amplitude, the complete description of which is important in the interpretation of data from precision electron-scattering experiments.

Assessing quality of life in patients with colorectal cancer: an update of the EORTC quality of life questionnaire

The European Organisation for Research and Treatment of Cancer (EORTC) has a portfolio of questionnaire modules to supplement the QLQ-C30 to assess patient reported outcomes in cancer clinical trials. This study updated the module for colorectal cancer. A review of the literature identified 20 articles that used the EORTC colorectal module. Eight papers did not report data from scales addressing sexual function and 8 added additional scales to assess ano-rectal function. Interviews with patients (n=79) and professionals (n=11) informed item selection, reduction and modification. A new 29 item module was devised and further patient interviews (n=120) examined its format and content validity. Patients found the new module acceptable with relevant content. The new module, the EORTC QLQ-CR29, is hypothesised as containing 6 scales and 11 single items. An international study examining its clinical and psychometric validity will be performed.

Precision measurements of the nucleon strange form factors at Q2 approximately 0.1 GeV2

We report new measurements of the parity-violating asymmetry A(PV) in elastic scattering of 3 GeV electrons off hydrogen and 4He targets with <theta(lab)> approximately 6.0 degrees . The 4He result is A(PV)=(+6.40+/-0.23(stat)+/-0.12(syst))x10(-6). The hydrogen result is A(PV)=(-1.58+/-0.12(stat)+/-0.04(syst))x10(-6). These results significantly improve constraints on the electric and magnetic strange form factors G(E)(s) and G(M)(s). We extract G(E)(s)=0.002+/-0.014+/-0.007 at <Q(2)>=0.077 GeV2, and G(E)(s)+0.09G(M)(s)=0.007+/-0.011+/-0.006 at <Q(2)>=0.109 GeV2, providing new limits on the role of strange quarks in the nucleon charge and magnetization distributions.

Determination of the pion charge form factor at Q2=1.60 and 2.45 (GeV/c)2

The 1H(e,e'pi+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (F(pi)) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which F(pi) is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative quantum chromodynamics prediction.

The influence of an enhanced recovery programme on clinical outcomes, costs and quality of life after surgery for colorectal cancer

OBJECTIVE

Optimizing peri-operative care using an enhanced recovery programme improves short-term outcomes following colonic resection. This study compared a prospective group of patients undergoing resection of colorectal cancer within an enhanced recovery programme, with a prospectively studied historic cohort receiving conventional care.

PATIENTS AND METHODS

Sixty patients underwent elective resection within an enhanced recovery programme (ERP). This incorporated pre-operative counselling, epidural analgesia, early feeding and mobilization. Clinical outcomes were compared with 86 prospectively studied historic control patients receiving conventional care (CC). All patients completed EORTC QLQ-C30, QLQ-CR38 and health economics questionnaires up to three months after surgery.

RESULTS

Baseline clinical data were similar in both groups. Postoperative hospital stay was significantly reduced in the ERP, with patients staying 49% as long as those in the CC group including convalescent hospital stay (95% CI 39% to 61%P < 0.001). There were no differences in the number of complications, readmissions or re-operations. There were no significant differences in quality of life or health economic outcomes.

CONCLUSION

Patients undergoing colorectal resection within an ERP stay in hospital half as long as those receiving conventional care, with no increased morbidity, deterioration in quality of life or increased cost.

Randomized clinical trial comparing laparoscopic and open surgery for colorectal cancer within an enhanced recovery programme

BACKGROUND

Laparoscopic resection of colorectal cancer may improve short-term outcome without compromising long-term survival or disease control. Recent evidence suggests that the difference between laparoscopic and open surgery may be less significant when perioperative care is optimized within an enhanced recovery programme. This study compared short-term outcomes of laparoscopic and open resection of colorectal cancer within such a programme.

METHODS

Between January 2002 and March 2004, 62 patients were randomized on a 2 : 1 basis to receive laparoscopic (n = 43) or open (n = 19) surgery. All were entered into an enhanced recovery programme. Length of hospital stay was the primary endpoint. Secondary outcomes of functional recovery, quality of life and cost were assessed for 3 months after surgery.

RESULTS

Demographics of the two groups were similar. Length of hospital stay after laparoscopic resection was 32 (95 per cent confidence interval (c.i.) 7 to 51) per cent shorter than for open resection (P = 0.018). Combined hospital, convalescent and readmission stay was 37 (95 per cent c.i. 10 to 56) per cent shorter (P = 0.012). The relative risk of complications, quality of life results and cost data were similar in the two groups.

CONCLUSION

Despite perioperative optimization of open surgery for colorectal cancer, short-term outcomes were better following laparoscopic surgery. There was no deterioration in quality of life or increased cost associated with the laparoscopic approach.

Ortho-para transition rate in mu-molecular hydrogen and the proton's induced pseudoscalar coupling gp

We report a measurement of the ortho-para transition rate in the p mu p molecule. The experiment was conducted at TRIUMF via the measurement of the time dependence of the 5.2 MeV neutrons from muon capture in liquid hydrogen. The measurement yielded an ortho-para rate Lambda op = (11.1 +/- 1.7 +/-(0.9)(0.6)) x 10(4) s(-1), which is substantially larger than the earlier result of Bardin et al. The result has striking implications for the proton's induced pseudoscalar coupling g(p), changing the value of g(p) obtained from the most precise ordinary muon capture measurement from 10.6 +/- 2.7 to 0.8 +/- 2.8, and from the sole radiative muon capture measurement from 12.2 +/- 1.1 to 10.6 +/- 1.2, bringing the latter result closer to theoretical predictions.

Strange-quark contributions to parity-violating asymmetries in the forward g0 electron-proton scattering experiment

We have measured parity-violating asymmetries in elastic electron-proton scattering over the range of momentum transfers 0.12 < or =Q2 < or =1.0 GeV2. These asymmetries, arising from interference of the electromagnetic and neutral weak interactions, are sensitive to strange-quark contributions to the currents of the proton. The measurements were made at Jefferson Laboratory using a toroidal spectrometer to detect the recoiling protons from a liquid hydrogen target. The results indicate nonzero, Q2 dependent, strange-quark contributions and provide new information beyond that obtained in previous experiments.

Perforation of the terminal ileum: a possible complication of nicorandil therapy

Recent reports have implicated nicorandil as a possible causative agent in the pathogenesis of anal and oral ulceration. We report a case of ulceration and perforation of the terminal ileum in a patient taking nicorandil. The possibility of an association between nicorandil therapy and gastrointestinal ulceration is discussed.

Upper gastrointestinal cancer pathology reporting: a regional audit to compare standards with minimum datasets

AIMS

Accurate pathological (pTNM) staging of oesophageal and gastric cancer provides important prognostic information. The aim of this study was to compare the standard of pathology reporting of oesophageal and gastric cancer resections from a cancer network with standards set by the Royal College of Pathologists.

METHODS

All reports for oesophageal and gastric cancer resections from the five hospitals in the cancer network in 2001 were collected. Individual items of information were compared with minimum datasets provided by the Royal College of Pathologists. Items were classified as "complete", "partially complete", or "absent".

RESULTS

One hundred and ten reports were audited (54 oesophageal and 56 gastric). Fourteen gastric and 17 oesophagectomy reports were over 75% complete. Clinically important missing data occurred most frequently for the pM component of TNM staging (pMx omitted in 87 reports) and completeness of resection expressed as a bold statement (absent in 50 reports). Twelve reports could not be classified because the specimen contained no residual tumour after neoadjuvant treatment.

CONCLUSION

The use of a standard proforma for reporting upper gastrointestinal cancers based on a minimum dataset provided by the Royal College of Pathologists is recommended, with modifications to allow for specimens with no tumour after neoadjuvant treatment.

Surgical site infection after groin hernia repair

Background

Post-discharge surveillance for 30 days is needed to determine the true incidence of surgical site infection (SSI). This study was undertaken to determine the incidence of, and risk factors for, SSI after hernia repair.

Methods

A total of 3150 patients who had undergone groin hernia repair in 32 Scottish hospitals were telephoned 10, 20 and 30 days after operation to screen for SSI. Patients who believed the wound to be infected were seen by a healthcare worker to confirm the diagnosis. Details of operations and risk factors were obtained by case-note review.

Results

One hundred and four patients (3·3 per cent) declined to give a contact telephone number, leaving 3046 patients who agreed to take part in the study. Some 108 patients (3·4 per cent) could not be contacted at any point, giving a response rate of 93·3 per cent. Complete data were available for 2665 patients (87·5 per cent); 140 (5·3 per cent) developed SSI and 57 (2·1 per cent) thought the wound infected but this was not confirmed by the healthcare worker. Patients given a prophylactic antibiotic had a lower incidence of SSI (P = 0·002), but neither increase in the American Society of Anesthesiologists grade of fitness for operation nor prolonged duration of operation was a significant risk factor for infection.

Conclusion

SSI after hernia repair is common and large clinical trials are required to determine whether the use of prophylactic antibiotics reduces the incidence of infection.

Telephone call contact for post-discharge surveillance of surgical site infections. A pilot, methodological study

Accurate determination of superficial surgical-site infection (SSI) requires post-discharge surveillance (PDS) for up to 30 days. To be useful for regional or national audit the method must be effective, inexpensive, and acceptable to patients. We assessed the role of telephone calls to patients in PDS of SSI in 3150 patients in 32 Scottish hospitals undergoing groin hernia repair during one year. Overall, 104 (3.3%) patients opted out of the audit by declining to give a contact telephone number, 96 (3.0%) could not provide a personal telephone contact number, and 12 could not be contacted, a compliance rate of 93.3%. Two thousand, nine hundred and thirty-eight patients were contacted at one or all of the call points, i.e. 10, 20, or 30 days postoperatively, from a single call centre by medical records clerks, working to a piloted protocol. Contact data, including contact at all three time points are available on 2665 (84.6%) patients. All patients who believed their wound to be infected were seen by a healthcare worker (HCW) to confirm or refute the diagnosis. Of the 2665 patients in whom complete data are available, 140 (5.3%) patients developed confirmed wound infection and a further 57 (2.1%) thought their wound was infected, but this was not confirmed by the HCW. Patients appeared to welcome the concept of telephone contact. Methods for identifying all patients eligible for surveillance need to be improved. However, we believe this method of patient contact could be appropriate for PDS in regional or national audit.

Laparoscopic excision of a triple gallbladder

Triplication of the gallbladder is a rare congenital anomaly of the biliary tract; there are only nine reported cases to date. We report a case in which laparoscopic cholecystectomy was performed in a patient with biliary colic and choledocholithiasis. Preoperative assessment with ultrasound and endoscopic retrograde cholangiopancreatography (ERCP) failed to reveal the eventual findings of a triple gallbladder. Successful excision of the triple gallbladder was carried out laparoscopically, and the final diagnosis was confirmed by the pathologist. The patient made an uneventful postoperative recovery and was free of gastrointestinal symptoms at follow-up. This case report describes the first laparoscopic excision of a triple gallbladder and highlights the importance of pre-/perioperative imaging to allow for the safe dissection of rare anomalies of the biliary tract via the laparoscopic approach.

Evidence of the effect of 'specialization' on the management, surgical outcome and survival from colorectal cancer in Wessex

BACKGROUND

A prospective audit of the management of colorectal cancer was established to investigate factors associated with variation in survival observed within the former Wessex region (population three million).

METHODS

Some 5173 patients (4562 surgically treated) with colorectal cancer diagnosed between 1991 and 1994 were followed for 5 years. Details of referral, diagnosis, surgical treatment, postoperative complications and outcomes were collected. The association between surgical outcomes and survival and both case volume and specialization (defined to include membership of the Association of Coloproctology of Great Britain and Ireland) was explored, accounting for variables with prognostic significance.

RESULTS

There was a statistically significant association between high-volume operators (more than 50 operations per year) and specialization. The greatest benefit was observed with respect to specialists versus non-specialists, in terms of a lower postoperative mortality rate (odds ratio 0.67 (95 per cent confidence interval (c.i. 0.53 to 0.84)), lower anastomotic leak rates (odds ratio 0.46 (c.i. 0.31 to 0.66)), higher local recurrence-free survival (hazard ratio 0.56 (0.44 to 0.71)) and better long-term survival (hazard ratio 0.76 (c.i. 0.71 to 0.83)).

CONCLUSION

There is a stronger association between surgical specialization in coloproctology and beneficial outcome than with high-volume caseloads. This is not entirely accounted for by case-mix or patient population, and is seen following colonic and rectal surgery and among patients with advanced disease.

Chronic pain and quality of life following open inguinal hernia repair

BACKGROUND

The aim was to determine the frequency and characteristics of chronic pain following open inguinal hernia repair and to identify risk factors for its development.

METHODS

This was a questionnaire survey of a historical cohort of patients who underwent inguinal hernia surgery in Aberdeen. The sample comprised all patients (n = 351) who underwent surgery between January 1995 and December 1997, and who were alive and resident in Grampian in October 1999. Outcome measures included self-report of pain persisting for more than 3 months after operation. Pain was characterized by means of the McGill Pain Questionnaire, and quality of life was assessed with the Short Form 36 (SF-36).

RESULTS

A total of 226 patients (64 per cent) completed the questionnaire, 67 (30 per cent) of whom reported chronic pain. Reported pain was predominantly neuropathic in character. Patients at increased risk of chronic pain were under 40 years old (P < 0.001), had day-case surgery (P = 0.004), had subsequent surgery on the same side (P < 0.005) and recalled pain before operation (P = 0.005). The SF-36 scores were significantly different in the social functioning, mental health and pain dimensions in patients with chronic pain.

CONCLUSION

Chronic pain occurred in 30 per cent of patients after open hernia repair, a higher frequency than has been reported previously. Several risk factors were identified and further prospective research is recommended.