Measurement of Neutral-Current K

Neutral-current production of K^{+} by atmospheric neutrinos is a background in searches for the proton decay p→K^{+}ν[over ¯]. Reactions such as νp→νK^{+}Λ are indistinguishable from proton decays when the decay products of the Λ are below detection threshold. Events with K^{+} are identified in MINERvA by reconstructing the timing signature of a K^{+} decay at rest. A sample of 201 neutrino-induced neutral-current K^{+} events is used to measure differential cross sections with respect to the K^{+} kinetic energy, and the non-K^{+} hadronic visible energy. An excess of events at low hadronic visible energy is observed relative to the prediction of the neut event generator. Good agreement is observed with the cross section prediction of the genie generator. A search for photons from π^{0} decay, which would veto a neutral-current K^{+} event in a proton decay search, is performed, and a 2σ deficit of detached photons is observed relative to the genie prediction.

Evidence of Coherent K

Neutrino-induced charged-current coherent kaon production ν_{µ}A→µ^{-}K^{+}A is a rare, inelastic electroweak process that brings a K^{+} on shell and leaves the target nucleus intact in its ground state. This process is significantly lower in rate than the neutrino-induced charged-current coherent pion production because of Cabibbo suppression and a kinematic suppression due to the larger kaon mass. We search for such events in the scintillator tracker of MINERvA by observing the final state K^{+}, µ^{-}, and no other detector activity, and by using the kinematics of the final state particles to reconstruct the small momentum transfer to the nucleus, which is a model-independent characteristic of coherent scattering. We find the first experimental evidence for the process at 3σ significance.

Evidence for Neutral-Current Diffractive π

The MINERvA experiment observes an excess of events containing electromagnetic showers relative to the expectation from Monte Carlo simulations in neutral-current neutrino interactions with mean beam energy of 4.5 GeV on a hydrocarbon target. The excess is characterized and found to be consistent with neutral-current π^{0} production with a broad energy distribution peaking at 7 GeV and a total cross section of 0.26±0.02(stat.)±0.08(sys.)×10^{-39} cm^{2}. The angular distribution, electromagnetic shower energy, and spatial distribution of the energy depositions of the excess are consistent with expectations from neutrino neutral-current diffractive π^{0} production from hydrogen in the hydrocarbon target. These data comprise the first direct experimental observation and constraint for a reaction that poses an important background process in neutrino-oscillation experiments searching for ν_{µ} to ν_{e} oscillations.

Three-dimensional ultrasound of pelvic floor: is there a correlation with delivery mode and persisting pelvic floor disorders 18-24 months after first delivery?

OBJECTIVE: Three-dimensional (3D) transperineal ultrasound has been shown to be a reliable and reproducible method for visualization of morphological changes in the female levator ani muscle. The aim of this study was to evaluate the relationship between persisting pelvic floor disorders 18-24 months after first delivery, biometric measurements of the pelvic floor and mode of delivery. METHODS: In this prospective observational study, we recruited on their second day after delivery 130 primiparous women. All were Caucasian and their pregnancies had been singleton with cephalic presentation. 3D transperineal ultrasound was performed, with standardized settings, on the second day (results published previously) and 18-24 months after delivery. Volumes were obtained at rest and on Valsalva maneuver and biometric measurements of the levator hiatus were determined in the axial plane. Obstetric and constitutional parameters were obtained from our clinical files and, 18-24 months after the delivery, a standardized questionnaire was used to evaluate persisting pelvic floor disorders. Ultrasound measurements at 18-24 months were compared according to clinical symptoms of pelvic floor disorders and mode of delivery, including a subgroup analysis of vaginal (spontaneous vs operative vaginal) and Cesarean (primary i.e. elective vs secondary i.e. after onset of labor) delivery groups. RESULTS: Seventy-seven (59%) women had complete follow-up at 18-24 months. Biometric measurements showed a significantly larger hiatal area in the vaginal delivery group than in the Cesarean section group 2 years after delivery (P < 0.01), whereas subgroup analysis within the vaginal and Cesarean delivery groups did not show significant differences. Although there was no statistical correlation between delivery mode and persisting stress urinary incontinence, women with persisting stress urinary incontinence 2 years after delivery had a larger hiatal area than did women without this clinical symptom (P < 0.01). There were no significant differences in hiatal dimensions in women with bladder urgency or dyspareunia. CONCLUSIONS: 3D transperineal ultrasound, which is easily accessible, can provide useful information on morphological changes of the female pelvic floor. Women with a spontaneous or operative vaginal first delivery had a significantly larger hiatal area and axial distension than did women whose first delivery was by Cesarean section, even 2 years after delivery. Performing 3D ultrasound after the first delivery may help to identify women at high risk for persisting pelvic floor disorders.

Three-dimensional ultrasound of the pelvic floor 2 days after first delivery: influence of constitutional and obstetric factors.

OBJECTIVES: Morphological changes of the pelvic floor during pregnancy and delivery can be visualized by three-dimensional (3D) perineal ultrasound. The aim of this study was to compare biometric measurements of the levator ani muscle according to maternal constitutional factors, delivery mode and size of the baby immediately after the first delivery. METHODS: In this prospective observational study, 130 primiparae were recruited (all of them Caucasians with singleton pregnancy and cephalic presentation). A 3D perineal ultrasound scan was performed on the second day after delivery with standardized settings. Volumes were obtained at rest and on Valsalva maneuver, and biometric measurements of the levator hiatus were determined in the axial plane. Different obstetric and constitutional parameters were obtained from our clinical files. RESULTS: All biometric measurements of the levator hiatus were significantly greater in the vaginal delivery group than in the Cesarean section group (P < 0.001), whereas subgroup analysis within the vaginal (spontaneous vs. operative vaginal) and Cesarean (primary vs. secondary) delivery groups did not show statistically significant differences. There was no demonstrable influence of maternal constitutional factors (age, body mass index (BMI)) or different obstetric parameters (length of second stage of labor, episiotomy, maternal injuries) on levator hiatus size postpartum, even in subgroups that delivered vaginally. Women with de novo postpartum stress incontinence showed a significantly higher mean levator hiatus transverse diameter and larger hiatal area on Valsalva maneuver (P < 0.05). There was also a positive but very weak correlation between the newborn's head circumference and hiatal dimensions at Valsalva maneuver (P < 0.05). CONCLUSIONS: Pelvic floor imaging by 3D ultrasound is easily accessible even on the first days after delivery and can provide useful information on morphological changes of the levator ani muscle. In our study, women with vaginal or operative vaginal delivery had a significantly larger hiatal area and transverse diameter than women who delivered by Cesarean section. Maternal constitutional factors (BMI, age) and duration of second stage of labor had no influence on the biometric measurements of hiatal area, whereas weight and head circumference of the baby showed a positive correlation with area of the levator hiatus.

Derivation of a closed form analytical expression for fluorescence recovery after photo bleaching in the case of continuous bleaching during read out.

Measurements of very slow diffusive processes in membranes, like the diffusion of integral membrane proteins, by fluorescence recovery after photo bleaching (FRAP) are hampered by bleaching of the probe during the read out of the fluorescence recovery. In the limit of long observation time (very slow diffusion as in the case of large membrane proteins), this bleaching may cause errors to the recovery function and thus provides error-prone diffusion coefficients. In this work we present a new approach to a two-dimensional closed form analytical solution of the reaction-diffusion equation, based on the addition of a dissipative term to the conventional diffusion equation. The calculation was done assuming (i) a Gaussian laser beam profile for bleaching the spot and (ii) that the fluorescence intensity profile emerging from the spot can be approximated by a two-dimensional Gaussian. The detection scheme derived from the analytical solution allows for diffusion measurements without the constraint of observation bleaching. Recovery curves of experimental FRAP data obtained under non-negligible read-out bleaching for native membranes (rabbit endoplasmic reticulum) on a planar solid support showed excellent agreement with the analytical solution and allowed the calculation of the lipid diffusion coefficient.