312 research outputs found
Long-range potentials and molecular resonances in an ultracold rydberg gas
We have calculated long-range molecular potentials of the ,
and symmetries between highly-excited rubidium atoms. Strong
potentials characterized by these symmetries are important in
describing interaction-induced phenomena in the excitation spectra of high
Rydberg states. Long-range molecular resonances are such phenomena and they
were first reported in S.M. Farooqi {\it et al.}, Phys. Rev. Lett. {\bf 91}
183002. One class of these resonances occurs at energies corresponding to
excited atom pairs . Such resonances are attributed to -mixing
due to Rydberg-Rydberg interactions so that otherwise forbidden molecular
transitions become allowed. We calculate molecular potentials in Hund's case
(c), use them to find the resonance lineshape and compare to experimental
results.Comment: 11 pages, 7 figure
Reconstructive Procedures after Total Gastrectomy for Gastric Cancer
Till this day, there are more than 60 described surgical procedures of the intestinal reconstructions after a total gastrectomy. In 1897, Schlatter reconstructed the digestive tract by creating a termino-lateral esophagojejunostomies that was the first successful total gastrectomy. Many of the total gastrectomy pioneers did the reconstruction by esophagoduodenostomy or by forming a loop esophagojejunostomy. The main reconstruction modalities after a total gastrectomy are a restitution of the intestinal continuity, without a preservation of the duodenal food passage (esophagojejunostomy with a Roux-en-Y configuration) and a restitution of the intestinal continuity with a preservation of the duodenal passage (esophagojejunostomy with Roux-en-Y configuration and forming of the lateral-terminal jejunoduodenal anastomosis double tract and jejunal interposition by Longmire). The surgeries in these categories can be combined with forming of an enteral pouch or a stomach reservoir which would simulate a reservoir of a normal intact stomach. The ideal reconstruction procedure after total gastrectomy should replace all lost functions of the stomach. Preservation of duodenal transit with replacement of the jejunal segment, the so-called physiological route, is now believed to be preferential for postoperative nutritional condition, prevents persistent postgastrectomy syndrome, and improves the quality of life. Reconstructive procedures which allow duodenal passage should be regarded as a key to physiological reconstruction
Unsupervised phenotypic clustering for determining clinical status in children with cystic fibrosis
BACKGROUND: Cystic Fibrosis (CF) is a multisystem disease in which assessing disease severity based on lung function alone may not be appropriate. The aim of the study was to develop a comprehensive machine-learning algorithm to assess clinical status independent of lung function in children. METHODS: A comprehensive prospectively collected clinical database (Toronto, Canada) was used to apply unsupervised cluster analysis. The defined clusters were then compared by current and future lung function, risk of future hospitalisation, and risk of future pulmonary exacerbation (PEx) treated with oral antibiotics. A K-Nearest Neighbours (KNN) algorithm was used to prospectively assign clusters. The methods were validated in a paediatric clinical CF dataset from Great Ormond Street Hospital (GOSH). RESULTS: The optimal cluster model identified four (A-D) phenotypic clusters based on 12 200 encounters from 530 individuals. Two clusters (A,B) consistent with mild disease were identified with high FEV1, and low risk of both hospitalisation and PEx treated with oral antibiotics. Two clusters (C,D) consistent with severe disease were also identified with low FEV1. Cluster D had the shortest time to both hospitalisation and PEx treated with oral antibiotics. The outcomes were consistent in 3124 encounters from 171 children at GOSH. The KNN cluster allocation error rate was low, at 2.5% (Toronto), and 3.5% (GOSH). CONCLUSION: Machine learning derived phenotypic clusters can predict disease severity independent of lung function and could be used in conjunction with functional measures to predict future disease trajectories in CF patients
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Exploring flexible polynomial regression as a method to align routine clinical outcomes with daily data capture through remote technologies
Data Availability:
The data that support the findings of this study are available from Great Ormond Street Hospital, but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are however available from the authors upon reasonable request and with permission of Great Ormond Street Hospital.Copyright © The Author(s) 2023. Background: Clinical outcomes are normally captured less frequently than data from remote technologies, leaving a disparity in volumes of data from these different sources. To align these data, flexible polynomial regression was investigated to estimate personalised trends for a continuous outcome over time. Methods: Using electronic health records, flexible polynomial regression models inclusive of a 1st up to a 4th order were calculated to predict forced expiratory volume in 1 s (FEV1) over time in children with cystic fibrosis. The model with the lowest AIC for each individual was selected as the best fit. The optimal parameters for using flexible polynomials were investigated by comparing the measured FEV1 values to the values given by the individualised polynomial. Results: There were 8,549 FEV1 measurements from 267 individuals. For individuals with > 15 measurements (n = 178), the polynomial predictions worked well; however, with < 15 measurements (n = 89), the polynomial models were conditional on the number of measurements and time between measurements. The method was validated using BMI in the same population of children. Conclusion: Flexible polynomials can be used to extrapolate clinical outcome measures at frequent time intervals to align with daily data captured through remote technologies.UCL, GOSH and Toronto SickKids studentship. GD is supported by a Future Leaders Fellowship from UK Research & Innovation (UKRI), Grant reference: MR/T041285. All research at Great Ormond Street Hospital NHS Foundation Trust and UCL Great Ormond Street Institute of Child Health is made possible by the NIHR Great Ormond Street Hospital Biomedical Research Centre
Spirometry reference equations for central European populations from school age to old age.
Spirometry reference values are important for the interpretation of spirometry results. Reference values should be updated regularly, derived from a population as similar to the population for which they are to be used and span across all ages. Such spirometry reference equations are currently lacking for central European populations. To develop spirometry reference equations for central European populations between 8 and 90 years of age. We used data collected between January 1993 and December 2010 from a central European population. The data was modelled using "Generalized Additive Models for Location, Scale and Shape" (GAMLSS). The spirometry reference equations were derived from 118'891 individuals consisting of 60'624 (51%) females and 58'267 (49%) males. Altogether, there were 18'211 (15.3%) children under the age of 18 years. We developed spirometry reference equations for a central European population between 8 and 90 years of age that can be implemented in a wide range of clinical settings
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Real-world effectiveness of airway clearance techniques in children with cystic fibrosis
Data Availability Statement - The study protocol is published open access. De-identified participant data are hosted in a secure DRE through GOSH DRIVE (www.goshdrive.com). Access to the data, data dictionary and informed consent forms through the DRE is available with permission from the corresponding author.Background Cystic fibrosis (CF) is commonly characterised by thick respiratory mucus. From diagnosis, people with CF are prescribed daily physiotherapy, including airway clearance techniques (ACTs). ACTs consume a large proportion of treatment time, yet the efficacy and effectiveness of ACTs are poorly understood. This study aimed to evaluate associations between the quality and quantity of ACTs and lung function in children and young people with CF. Methods Project Fizzyo, a longitudinal observational cohort study in the UK, used remote monitoring with electronic pressure sensors attached to four different commercial ACT devices to record real-time, breath-by-breath pressure data during usual ACTs undertaken at home over 16 months in 145 children. ACTs were categorised either as conformant or not with current ACT recommendations based on breath pressure and length measurements, or as missed treatments if not recorded. Daily, weekly and monthly associations between ACT category and lung function were investigated using linear mixed effects regression models adjusting for clinical confounders. Results After exclusions, 45 224 ACT treatments (135 individuals) and 21 069 days without treatments (141 individuals) were analysed. The mean±SD age of participants was 10.2±2.9 years. Conformant ACTs (21%) had significantly higher forced expiratory volume in 1 s (FEV1) (mean effect size 0.23 (95% CI 0.19–0.27) FEV1 % pred per treatment) than non-conformant (79%) or missed treatments. There was no benefit from non-conformant or missed treatments and no significant difference in FEV1 between them (mean effect size 0.02 (95% CI −0.01–0.05) FEV1 % pred per treatment). Conclusions ACTs are beneficial when performed as recommended, but most people use techniques that do not improve lung function. Work is needed to monitor and improve ACT quality and to increase the proportion of people doing effective airway clearance at home.UK Research and Innovation
MR/T041285/1
Rosetrees Trust
M712
Cystic Fibrosis Trust
CEA010
Great Ormond Street Hospital for Children
Higher Education Funding Council for England
KEI2017–01–04
Hospital for Sick Children
University College London
Partners Awar
ELECTRO-ACOUSTIC ANALOGIES BETWEEN THERMOELASTIC COMPONENT OF THE PHOTOACOUSTIC SIGNAL AND LOW-PASS RC FILTER
This paper presents a new approach to the thermal characterization of aluminum, based on the electro-acoustic analogy between the thermoelastic component of the photoacoustic signal and the passive RC low-pass filter. The analogies were used to calculate the characteristic thermoelastic cut-off frequencies of the photoacoustic component and obtain their relationship with the thickness of the aluminum samples. Detailed numerical analysis showed that the required relationship is linear in the log-log scale and can serve as a reference curve for the given material. The results of the numerical analysis were also confirmed experimentally
Observation of coherent many-body Rabi oscillations
A two-level quantum system coherently driven by a resonant electromagnetic
field oscillates sinusoidally between the two levels at frequency
which is proportional to the field amplitude [1]. This phenomenon, known as the
Rabi oscillation, has been at the heart of atomic, molecular and optical
physics since the seminal work of its namesake and coauthors [2]. Notably, Rabi
oscillations in isolated single atoms or dilute gases form the basis for
metrological applications such as atomic clocks and precision measurements of
physical constants [3]. Both inhomogeneous distribution of coupling strength to
the field and interactions between individual atoms reduce the visibility of
the oscillation and may even suppress it completely. A remarkable
transformation takes place in the limit where only a single excitation can be
present in the sample due to either initial conditions or atomic interactions:
there arises a collective, many-body Rabi oscillation at a frequency
involving all N >> 1 atoms in the sample [4]. This is true even
for inhomogeneous atom-field coupling distributions, where single-atom Rabi
oscillations may be invisible. When one of the two levels is a strongly
interacting Rydberg level, many-body Rabi oscillations emerge as a consequence
of the Rydberg excitation blockade. Lukin and coauthors outlined an approach to
quantum information processing based on this effect [5]. Here we report initial
observations of coherent many-body Rabi oscillations between the ground level
and a Rydberg level using several hundred cold rubidium atoms. The strongly
pronounced oscillations indicate a nearly complete excitation blockade of the
entire mesoscopic ensemble by a single excited atom. The results pave the way
towards quantum computation and simulation using ensembles of atoms
Response Factors to Pegylated Interferon-Alfa/Ribavirin Treatment in Chronic Hepatitis C Patients Genotype 1b
Hepatitis C virus infection is the most common chronic blood-borne infection and one of the most important causes of chronic liver disease. Knowing the predictors associated with pegylated interferon/ribavirin (PEG-IFN/RBV) combination therapy response is important for evidence-based treatment recommendations. The goal of this study was to identify host and viral factors of response to PEG-IFN/RBV treatment in chronic hepatitis C genotype 1b patients. We have examined the relationship between gender, age, level of alanine aminotransferase (ALT), viral load and liver fibrosis progression on therapy response. ALT level and viral load were evaluated before starting treatment with combination therapy. The elevated levels of ALT and route of HCV transmission were found to be significantly associated with the response to therapy in HCV-infected patients. Our findings may be useful for estimating a patients likelihood Of achieving sustained viral response
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