Random variation in rectal position during radiotherapy for prostate cancer is two to three times greater than that predicted from prostate motion

Objective:

Radiotherapy for prostate cancer does not explicitly take into account daily variation in the position of the rectum. It is important to accurately assess accumulated dose (D_A) to the rectum in order to understand the relationship between dose and toxicity. The primary objective of this work was to quantify systematic (Σ) and random (σ) variation in the position of the rectum during a course of prostate radiotherapy.

Methods:

The rectum was manually outlined on the kilo-voltage planning scan and 37 daily mega-voltage image guidance scans for 10 participants recruited to the VoxTox study. The femoral heads were used to produce a fixed point to which all rectal contours were referenced.

Results:

Σ [standard deviation (SD) of means] between planning and treatment was 4.2 mm in the anteroposterior (AP) direction and 1.3 mm left–right (LR). σ (root mean square of SDs) was 5.2 mm AP and 2.7 mm LR. Superior–inferior variation was less than one slice above and below the planning position.

Conclusion:

Our results for Σ are in line with published data for prostate motion. σ, however, was approximately twice as great as that seen for prostate motion. This suggests that D_A may differ from planned dose in some patients treated with radiotherapy for prostate cancer.

Advances in knowledge:

This work is the first to use daily imaging to quantify Σ and σ of the rectum in prostate cancer. σ was found to be greater than published data, providing strong rationale for further investigation of individual D_A.

Percolation-based risk index for pathogen invasion: application to soilborne disease in propagation systems

Propagation systems for seedling growth play a major role in agriculture, and in notable cases (such as organic systems), are under constant threat from soil and seedborne fungal plant pathogens such as Rhizoctonia solani or Pythium spp. Yet, to date little is known that links the risk of disease invasion to the host density, which is an agronomic characteristic that can be readily controlled. We introduce here, for the first time in an agronomic system, a percolation framework to analyze the link. We set up an experiment to study the spread of the ubiquitous fungus R. solani in replicated propagation systems with different planting densities, and fit a percolation-based epidemiological model to the data using Bayesian inference methods. The estimated probability of pathogen transmission between infected and susceptible plants is used to calculate the risk of invasion. By comparing the transmission probability and the risk values obtained for different planting densities, we are able to give evidence of a nonlinear relationship between disease invasion and the inter-plant spacing, hence to demonstrate the existence of a spatial threshold for epidemic invasion. The implications and potential use of our methods for the evaluation of disease control strategies are discussed.

Measurement of the forward energy flow in pp collisions at [Formula: see text]

The energy flow created in pp collisions at [Formula: see text] is studied within the pseudorapidity range 1.9<η<4.9 with data collected by the LHCb experiment. The measurements are performed for inclusive minimum-bias interactions, hard scattering processes and events with an enhanced or suppressed diffractive contribution. The results are compared to predictions given by Pythia-based and cosmic-ray event generators, which provide different models of soft hadronic interactions.

First observation of the decay Bs2*(5840)(0)→B*+ K- and studies of excited Bs(0) mesons

The properties of the orbitally excited (L=1) Bs(0) states are studied by using 1.0  fb(-1) of pp collisions at sqrt[s]=7  TeV collected with the LHCb detector. The first observation of the Bs2*(5840)(0) meson decaying to B*+ K- is reported, and the corresponding branching fraction measured relative to the B+ K- decay mode. The Bs1(5830)(0)→B*+ K- decay is observed as well. The width of the Bs2*(5840)(0) state is measured for the first time, and the masses of the two states are determined with the highest precision to date. The observation of the Bs2*(5840)(0)→B*+ K- decay favors the spin-parity assignment J(P)=2+ for the Bs2*(5840)(0) meson. In addition, the most precise measurement of the mass difference m(B*+)-m(B+)=45.01±0.30(stat)±0.23(syst)  MeV/c(2) is obtained.

Observation of D0-D0 oscillations

We report a measurement of the time-dependent ratio of D(0) → K(+) π- to D(0) → K(-) π(+) decay rates in D(*+)-tagged events using 1.0 fb(-1) of integrated luminosity recorded by the LHCb experiment. We measure the mixing parameters x('2) = (-0.9 ± 1.3) × 10(-4), y' = (7.2 ± 2.4) × 10(-3), and the ratio of doubly-Cabibbo-suppressed to Cabibbo-favored decay rates R(D) = (3.52 ± 0.15) × 10^{-3}, where the uncertainties include statistical and systematic sources. The result excludes the no-mixing hypothesis with a probability corresponding to 9.1 standard deviations and represents the first observation of D0-D0 oscillations from a single measurement.

Measurement of the CP asymmetry in B(0)→K(*0)μ(+)μ(-) decays

A measurement of the CP asymmetry in B(0)→K(*0)μ(+)μ(-) decays is presented, based on 1.0 fb(-1) of pp collision data recorded by the LHCb experiment during 2011. The measurement is performed in six bins of invariant mass squared of the μ(+)μ(-) pair, excluding the J/ψ and ψ(2S) resonance regions. Production and detection asymmetries are removed using the B(0)→J/ψK(*0) decay as a control mode. The integrated CP asymmetry is found to be -0.072±0.040(stat)±0.005(syst), consistent with the standard model.

First evidence for the decay B(s)(0)→μ+ μ-

A search for the rare decays B(s)(0)→μ+ μ- and B(0)→μ+ μ- is performed with data collected in 2011 and 2012 with the LHCb experiment at the Large Hadron Collider. The data samples comprise 1.1  fb(-1) of proton-proton collisions at sqrt[s]=8  TeV and 1.0  fb(-1) at sqrt[s]=7  TeV. We observe an excess of B(s)(0)→μ+ μ- candidates with respect to the background expectation. The probability that the background could produce such an excess or larger is 5.3×10(-4) corresponding to a signal significance of 3.5 standard deviations. A maximum-likelihood fit gives a branching fraction of B(B(s)(0)→μ+ μ-)=(3.2(-1.2)(+1.5))×10(-9), where the statistical uncertainty is 95% of the total uncertainty. This result is in agreement with the standard model expectation. The observed number of B(0)→μ+ μ- candidates is consistent with the background expectation, giving an upper limit of B(B(0)→μ+ μ-)<9.4×10(-10) at 95% confidence level.

Measurements of B(c)+ production and mass with the B(c)+ → J/ψπ+ decay

Measurements of B(c)(+) production and mass are performed with the decay mode B(c)(+)→J/ψπ(+) using 0.37 fb(-1) of data collected in pp collisions at √[s]=7 TeV by the LHCb experiment. The ratio of the production cross section times branching fraction between the B(c)(+)→J/ψπ(+) and the B(+)→J/ψK(+) decays is measured to be (0.68±0.10(stat)±0.03(syst)±0.05(lifetime))% for B(c)(+) and B(+) mesons with transverse momenta p(T)>4 GeV/c and pseudorapidities 2.5<η<4.5. The B(c)(+) mass is directly measured to be 6273.7±1.3(stat)±1.6(syst) MeV/c(2), and the measured mass difference with respect to the B(+) meson is M(B(c)(+))-M(B(+))=994.6±1.3(stat)±0.6(syst) MeV/c(2).

Parent views of the positive contributions of elementary and high school-aged children with autism spectrum disorders and Down syndrome

BACKGROUND

Much is known about the hardships associated with parenting a child with a disability, but few studies have examined the broader contributions of the child to family life or society.

METHODS

The study involved qualitative analysis of interviews with 16 families of children with autism spectrum disorder or Down syndrome at critical transition periods (entry to elementary or high school), targeting their perceptions of benefits.

RESULTS

Parents discussed a wide range of benefits beyond the personal level, including parental, family and societal benefits. Exploratory group comparisons indicated that parents of high school-aged children were more likely to mention family-level and societal benefits.

CONCLUSIONS

The findings suggest that raising a child with a disability can trigger role-related decisions that lead to a series of resiliency-related processes and cascading benefits. The findings inform practitioners about the nature of potential positive experiences that can be shared with families starting out on their journey, allowing parents to recognize the positive dimensions of raising a child with a disability in addition to the hardships.

Observation of excited Λ(b)(0) baryons

Using pp collision data corresponding to 1.0 fb(-1) integrated luminosity collected by the LHCb detector, two narrow states are observed in the Λ(b)(0)π(+)π(-) spectrum with masses 5911.97±0.12(stat)±0.02(syst)±0.66(Λ(b)(0) mass) MeV/c(2) and 5919.77±0.08(stat)±0.02(syst)±0.66(Λ(b)(0) mass) MeV/c(2). The significances of the observations are 5.2 and 10.2 standard deviations, respectively. These states are interpreted as the orbitally excited Λ(b)(0) baryons, Λ(b)(*0)(5912) and Λ(b)(*0)(5920).

Measurement of the B¯(s)(0) effective lifetime in the J/ψf0(980) final state

The effective lifetime of the B ¯(s)(0) meson in the decay mode B¯(s)(0)→J/ψf(0)(980) is measured using 1.0 fb(-1) of data collected in pp collisions at √s=7 TeV with the LHCb detector. The result is 1.700±0.040±0.026 ps, where the first uncertainty is statistical and the second systematic. As the final state is CP-odd, and CP violation in this mode is measured to be small, the lifetime measurement can be translated into a measurement of the decay width of the heavy B¯(s)(0) mass eigenstate, Γ(H)=0.588±0.014±0.009 ps(-1).

Observation of B0→D¯(0)K(+)K(-) and evidence for B(s)(0)→D¯(0)K(+)K(-)

The first observation of the decay B0→D¯(0)K(+)K(-) is reported from an analysis of 0.62 fb(-1) of pp collision data collected with the LHCb detector. Its branching fraction is measured relative to that of the topologically similar decay B(0)→D ¯(0)π(+)π(-) to be (B(B(0)→D¯(0)K(+)K(-))/B(B(0)→D¯(0)π(+)π(-))=0.056±0.011±0.007,where the first uncertainty is statistical and the second is systematic. The significance of the signal is 5.8σ. Evidence, with 3.8σ significance, for B(s)(0)→D¯(0)K(+)K(-) decays is also presented. The relative branching fraction is measured to be B(B(s)(0)→D¯(0)K(+)K(-))/B(B(0)→D¯(0)K(+)K(-))=0.90±0.27±0.20. These channels are of interest to study the mechanisms behind hadronic B decays, and open new possibilities for CP violation analyses with larger data sets.

Measurement of relative branching fractions of B decays to ψ(2S) and J/ψ mesons

The relative rates of B-meson decays into J/ψ and ψ(2S) mesons are measured for the three decay modes in pp collisions recorded with the LHCb detector. The ratios of branching fractions ([Formula: see text]) are measured to be [Formula: see text] where the third uncertainty is from the ratio of the ψ(2S) and J/ψ branching fractions to μ⁺μ^-.

Measurement of ψ(2S) meson production in pp collisions at [Formula: see text]

The differential cross-section for the inclusive production of ψ(2S) mesons in pp collisions at [Formula: see text] has been measured with the LHCb detector. The data sample corresponds to an integrated luminosity of 36 pb^-1. The ψ(2S) mesons are reconstructed in the decay channels ψ(2S)→μ⁺μ^- and ψ(2S)→J/ψπ⁺π^-, with the J/ψ meson decaying into two muons. Results are presented both for promptly produced ψ(2S) mesons and for those originating from b-hadron decays. In the kinematic range p_T(ψ(2S))≤16 GeV/c and 2<y(ψ(2S))≤4.5 we measure [Formula: see text] where the last uncertainty on the prompt cross-section is due to the unknown ψ(2S) polarization. Recent QCD calculations are found to be in good agreement with our measurements. Combining the present result with the LHCb J/ψ measurements we determine the inclusive branching fraction [Formula: see text] where the last uncertainty is due to the [Formula: see text], [Formula: see text] and [Formula: see text] branching fraction uncertainties.

First observation of the decay B(c)+ → J/ψπ(+) π- π+

The decay B(c)(+) → J/ψπ(+) π(-) π(+) is observed for the first time, using 0.8 fb(-1) of pp collisions at sqrt[s] = 7 TeV collected by the LHCb experiment. The ratio of branching fractions B(B(c)(+) → J/ψπ(+) π(-) π(+))/B(B(c)(+)→J/ψπ^{+}) is measured to be 2.41 ± 0.30 ± 0.33, where the first uncertainty is statistical and the second is systematic. The result is in agreement with theoretical predictions.

Determination of the sign of the decay width difference in the B(s)(0) system

The interference between the K+ K- S-wave and P-wave amplitudes in B(s)(0) → J/ψK+ K- decays with the K+ K- pairs in the region around the ϕ(1020) resonance is used to determine the variation of the difference of the strong phase between these amplitudes as a function of K+ K- invariant mass. Combined with the results from our CP asymmetry measurement in B(s)(0) → J/ψϕ decays, we conclude that the B(s)(0) mass eigenstate that is almost CP = +1 is lighter and decays faster than the mass eigenstate that is almost CP = -1. This determines the sign of the decay width difference ΔΓ(s) ≡ Γ(L) - Γ(H) to be positive. Our result also resolves the ambiguity in the past measurements of the CP violating phase ϕ(s) to be close to zero rather than π. These conclusions are in agreement with the standard model expectations.

Strong constraints on the rare decays B(s)(0) → μ+ μ- and B0 → μ+ μ-

A search for B(s)(0) → μ+ μ- and B0 → μ+ μ decays is performed using 1.0  fb(-1) of pp collision data collected at sqrt[s] = 7  TeV with the LHCb experiment at the Large Hadron Collider. For both decays, the number of observed events is consistent with expectation from background and standard model signal predictions. Upper limits on the branching fractions are determined to be B(B(s)(0) → μ+ μ-) < 4.5(3.8)×10(-9) and B(B0 → μ+ μ-) < 1.0(0.81)×10(-9) at 95% (90%) confidence level.

Opposite-side flavour tagging of B mesons at the LHCb experiment

The calibration and performance of the opposite-side flavour tagging algorithms used for the measurements of time-dependent asymmetries at the LHCb experiment are described. The algorithms have been developed using simulated events and optimized and calibrated with B⁺→J/ψK⁺, B⁰→J/ψK^∗0 and B⁰→D^∗-μ⁺ν_μ decay modes with 0.37 fb^-1 of data collected in pp collisions at [Formula: see text] during the 2011 physics run. The opposite-side tagging power is determined in the B⁺→J/ψK⁺ channel to be (2.10±0.08±0.24) %, where the first uncertainty is statistical and the second is systematic.

Measurement of production in collisions at [Formula: see text]

The production of ϒ(1S), ϒ(2S) and ϒ(3S) mesons in proton-proton collisions at the centre-of-mass energy of [Formula: see text] is studied with the LHCb detector. The analysis is based on a data sample of 25 pb-1 collected at the Large Hadron Collider. The ϒ mesons are reconstructed in the decay mode ϒ→μ+μ- and the signal yields are extracted from a fit to the μ+μ- invariant mass distributions. The differential production cross-sections times dimuon branching fractions are measured as a function of the ϒ transverse momentum pT and rapidity y, over the range pT <15 GeV/c and 2.0 Collapse

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