Time Calibration of the LHCb muon System

The LHCb muon System consists of about 122,000 frontend channels. It plays a basic role in the first trigger level. The trigger requires 95% efficiency in muon tracks detection. It is then necessary to reach a system time alignment at the level of about 2 ns. This alignment must be monitored against possible fluctuations due to changes in the detector operating conditions. We describe the custom instrumentation implemented at system level for time calibration, the strategy adopted, the procedure to be followed both for system alignment and monitoring, the control program realized for this purpose. We also illustrate first results obtained during the detector commissioning in the LHCb pit

Increased absorption by coarse aerosol particles over the Gangetic–Himalayan region

Each atmospheric aerosol type has distinctive light-absorption characteristics related to its physical/chemical properties. Climate models treat black carbon as the main light-absorbing component of carbonaceous atmospheric aerosols, while absorption by some organic aerosols is also considered, particularly at ultraviolet wavelengths. Most absorbing aerosols are assumed to be < 1 μm in diameter (sub-micron). Here we present results from a recent field study in India, primarily during the post-monsoon season (October–November), suggesting the presence of absorbing aerosols sized 1–10 μm. Absorption due to super-micron-sized particles was nearly 30% greater than that due to smaller particles. Periods of increased absorption by larger particles ranged from a week to a month. Radiative forcing calculations under clear-sky conditions show that super-micron particles account for nearly 44% of the total aerosol forcing. The origin of the large aerosols is unknown, but meteorological conditions indicate that they are of local origin. Such economic and habitation conditions exist throughout much of the developing world. Hence, large absorbing particles could be an important component of the regional-scale atmospheric energy balance

Role of 0.4% glyceryl trinitrate ointment after haemorrhoidectomy: results of a prospective randomised study

INTRODUCTION: Conventional haemorrhoidectomy (CH) is well known to cause significant post-operative pain and delayed return to daily activities. Both surgical wounds and sphincterial apparatus spasms are likely responsible for the pain. In this study, we evaluated the role of glyceryl trinitrate ointment (GTN) in reducing post-operative pain, ameliorating wound healing and recovery after CH. PATIENTS AND METHODS: Between 01/08 and 12/11, 203 patients with symptomatic haemorrhoids were enrolled in the study and received (103 patients) or not (100 patients) 0.4 % GTN ointment for 6 weeks after surgery. Pain was assessed using a 10-cm linear visual analogue scale (VAS). Data on post-operative pain, wound secretion and bleeding, return to normal activities and complications were recorded. Data were analysed using Fisher's exact and Mann-Whitney tests. RESULTS: GTN-treated group experienced significantly less pain during the first week after surgery (p < 0.0001). This difference was more evident starting from post-operative day 4 (p < 0.0001). A significant higher percentage of untreated patients experienced severe pain (mean VAS score > 7) (10 % vs 31 %). There were significant differences in terms of secretion time (p = 0.0052) and bleeding time (p = 0.02) in favor of GTN. In addition, the duration of itching was less in the GTN group (p = 0.0145). Patients treated with GTN were able to an early return to daily activities compared to untreated (p < 0.0001). Fifteen GTN-treated patients (14.6 %) discontinued the application because of local discomfort and headache. CONCLUSIONS: GTN ointment enhances significantly post-operative recovery, reducing pain in terms of duration and intensity. This effect might be secondary to a faster wound healing expressed by reduced secretion, bleeding and itching time

Ligation of the intersphincteric fistula tract (LIFT) to treat anal fistula: early results from a prospective observational study

Ligation of the intersphincteric tract (LIFT), a novel sphincter-saving technique, has been recently described with promising results. Literature data are still scant. In this prospective observational study, we present our experience with this technique

Measurement of the front-end dead-time of the LHCb muon detector and evaluation of its contribution to the muon detection inefficiency

A method is described which allows to deduce the dead-time of the front-end electronics of the LHCb muon detector from a series of measurements performed at different luminosities at a bunch-crossing rate of 20 MHz. The measured values of the dead-time range from 70 ns to 100 ns. These results allow to estimate the performance of the muon detector at the future bunch-crossing rate of 40 MHz and at higher luminosity

Performance of the LHCb muon system with cosmic rays

The LHCb Muon system performance is presented using cosmic ray events collected in 2009. These events allowed to test and optimize the detector configuration before the LHC start. The space and time alignment and the measurement of chamber efficiency, time resolution and cluster size are described in detail. The results are in agreement with the expected detector performance.Comment: Submitted to JINST and accepte

Universal Vectorial and Ultrasensitive Nanomechanical Force Field Sensor

Miniaturization of force probes into nanomechanical oscillators enables ultrasensitive investigations of forces on dimensions smaller than their characteristic length scale. Meanwhile it also unravels the force field vectorial character and how its topology impacts the measurement. Here we expose an ultrasensitive method to image 2D vectorial force fields by optomechanically following the bidimensional Brownian motion of a singly clamped nanowire. This novel approach relies on angular and spectral tomography of its quasi frequency-degenerated transverse mechanical polarizations: immersing the nanoresonator in a vectorial force field does not only shift its eigenfrequencies but also rotate eigenmodes orientation as a nano-compass. This universal method is employed to map a tunable electrostatic force field whose spatial gradients can even take precedence over the intrinsic nanowire properties. Enabling vectorial force fields imaging with demonstrated sensitivities of attonewton variations over the nanoprobe Brownian trajectory will have strong impact on scientific exploration at the nanoscale

Prevalence of Defaecatory Disorders in Morbidly Obese Patients Before and After Bariatric Surgery

BACKGROUND: The prevalence of obesity is increasing worldwide and has lately reached epidemic proportions in western countries. Several epidemiological studies have consistently shown that both overweight and obesity are important risk factors for the development of various functional defaecatory disorders (DDs), including faecal incontinence and constipation. However, data on their prevalence as well as effectiveness of bariatric surgery on their correction are scant. The primary objective of this study was to estimate the effect of morbid obesity on DDs in a cohort of patients listed for bariatric surgery. We also evaluated preliminary results of the effects of sleeve gastrectomy on these disorders. PATIENTS AND METHODS: A questionnaire-based study was proposed to morbidly obese patients having bariatric surgery. Data included demographics, past medical, surgical and obstetrics histories, as well as obesity related co-morbidities. Wexner Constipation Score (WCS) and the Faecal Incontinence Severity Index (FISI) questionnaires were used to evaluate constipation and incontinence. For the purpose of this study, we considered clinically relevant a WCS ≥5 and a FISI score ≥10. The same questionnaires were completed at 3 and 6 months follow-up after surgery. RESULTS: A total of 139 patients accepted the study and 68 underwent sleeve gastrectomy and fully satisfied our inclusion criteria with a minimum follow-up of 6 months. Overall, mean body mass index (BMI) at listing was 47 ± 7 kg/m(2) (range 35-67 kg/m(2)). Mean WCS was 4.1 ± 4 (range 0-17), while mean FISI score (expressed as mean±standard deviation) was 9.5 ± 9 (range 0-38). Overall, 58.9% of the patients reported DDs according to the above-mentioned scores. Twenty-eight patients (20%) had WCS ≥5. Thirty-five patients (25%) had a FISI ≥10 while 19 patients (13.7%) reported combined abnormal scores. Overall, DDs were more evident with the increase of obesity grade: Mean BMI decreased significantly from 47 ± 7 to 36 ± 6 and to 29 ± 4 kg/m(2) respectively at 3 and 6 months after surgery (p < 0.0001). According to the BMI decrease, the mean WCS decreased from 3.7 ± 3 to 3.1 ± 4 and to 1.6 ± 3 respectively at 3 and 6 months (p = 0.02). Similarly, the FISI score decreased from 10 ± 8 to 3 ± 4 and to 1 ± 2 respectively at 3 and 6 months (p = 0.0001). CONCLUSIONS: Defaecatory disorders are common in morbidly obese patients. The risk of DDs increases with BMI. Bariatric surgery reduces DDs, mainly faecal incontinence, and these findings correlated with BMI reduction

A facility to Search for Hidden Particles (SHiP) at the CERN SPS

A new general purpose fixed target facility is proposed at the CERN SPS accelerator which is aimed at exploring the domain of hidden particles and make measurements with tau neutrinos. Hidden particles are predicted by a large number of models beyond the Standard Model. The high intensity of the SPS 400~GeV beam allows probing a wide variety of models containing light long-lived exotic particles with masses below ${\cal O}$(10)~GeV/c$^2$, including very weakly interacting low-energy SUSY states. The experimental programme of the proposed facility is capable of being extended in the future, e.g. to include direct searches for Dark Matter and Lepton Flavour Violation.Comment: Technical Proposa