27 research outputs found
On the large order behaviour of the Potts model
Following the work by Houghton, Reeve and Wallace about an alternative
formulation of the limit of the state Potts model in field
theory for the large order behaviour of the perturbative expansion, we
generalise their technique to all by establishing an equivalence in
perturbation theory order by order with another bosonic field theory.
Restricting ourselves to a cubic interaction, we obtain an explicit expression
(in terms of~) for the large order behaviour of the partition function.Comment: 16 pages, require TeXdra
Image restoration using the Q-Ising spin glass
We investigate static and dynamic properties of gray-scale image restoration
(GSIR) by making use of the Q-Ising spin glass model, whose ladder symmetry
allows to take in account the distance between two spins. We thus give an
explicit expression of the Hamming distance between the original and restored
images as a function of the hyper-parameters in the mean field limit. Finally,
numerical simulations for real-world pictures are carried out to prove the
efficiency of our model.Comment: 27pages, 13figures, revte
Diagnostic and prognostic role of liquid biopsy in non-small cell lung cancer: evaluation of circulating biomarkers
Lung cancer is still one of the main causes of cancer-related death, together with prostate and colorectal
cancers in males and breast and colorectal cancers in females. The prognosis for non-small cell lung cancer
(NSCLC) is strictly dependent on feasibility of a complete surgical resection of the tumor at diagnosis. Since
surgery is indicated only in early stages tumors, it is necessary to anticipate the timing of diagnosis in clinical
practice. In the diagnostic and therapeutic pathway for NSCLC, sampling of neoplastic tissue is usually
obtained using invasive methods that are not free from disadvantages and complications. A valid alternative
to the standard biopsy is the liquid biopsy (LB), that is, the analysis of samples from peripheral blood, urine,
and other biological fluids, with a simple and non-invasive collection. In particular, it is possible to detect
in the blood different tumor derivatives, such as cell-free DNA (cfDNA) with its subtype circulating tumor
DNA (ctDNA), cell-free RNA (cfRNA), and circulating tumor cells (CTCs). Plasma-based testing seems to have
several advantages over tumor tissue biopsy; firstly, it reduces medical costs, risk of complications related
to invasive procedures, and turnaround times; moreover, the analysis of genes alteration, such as EGFR, ALK,
ROS1, and BRAF is faster and safer with this method, compared to tissue biopsy. Despite all these advantages,
the evidences in literatures indicate that assays performed on liquid biopsies have a low sensitivity, making
them unsuitable for screening in lung cancer at the current state. This is caused by lack of standardization
in sampling and preparation of specimen and by the low concentration of biomarkers in the bloodstream.
Instead, routinely use of LB should be preferred in revaluation of patients with advanced NSCLC resistant to
chemotherapy, due to onset of new mutations
Image restoration using the chiral Potts spin-glass
We report on the image reconstruction (IR) problem by making use of the
random chiral q-state Potts model, whose Hamiltonian possesses the same gauge
invariance as the usual Ising spin glass model. We show that the pixel
representation by means of the Potts variables is suitable for the gray-scale
level image which can not be represented by the Ising model. We find that the
IR quality is highly improved by the presence of a glassy term, besides the
usual ferromagnetic term under random external fields, as very recently pointed
out by Nishimori and Wong. We give the exact solution of the infinite range
model with q=3, the three gray-scale level case. In order to check our
analytical result and the efficiency of our model, 2D Monte Carlo simulations
have been carried out on real-world pictures with three and eight gray-scale
levels.Comment: RevTex 13 pages, 10 figure
Changes in white matter as determinant of global functional decline in older independent outpatients: three year follow-up of LADIS (leukoaraiosis and disability) study cohort
Objective To assess the impairment in daily living activities in older people with age related changes in white matter according to the severity of these changes
Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study
Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research