Monte Carlo studies of the square Ising model with next-nearest-neighbor interactions

We apply a new entropic scheme to study the critical behavior of the square-lattice Ising model with nearest- and next-nearest-neighbor antiferromagnetic interactions. Estimates of the present scheme are compared with those of the Metropolis algorithm. We consider interactions in the range where superantiferromagnetic (SAF) order appears at low temperatures. A recent prediction of a first-order transition along a certain range (0.5-1.2) of the interaction ratio $(R=J_{nnn}/J_{nn})$ is examined by generating accurate data for large lattices at a particular value of the ratio $(R=1)$. Our study does not support a first-order transition and a convincing finite-size scaling analysis of the model is presented, yielding accurate estimates for all critical exponents for R=1 . The magnetic exponents are found to obey ``weak universality'' in accordance with a previous conjecture.Comment: 9 pages, 7 figures, Proceedings of the third NEXT Sigma Phi International Conference, kolymbari, Greece (2005

A systematic review and meta-analysis on fetal ovarian cysts: impact of size, appearance and prenatal aspiration

The objective of the study is to compare outcomes of ultrasound-guided aspiration of fetal ovarian cysts with conservative management. METHOD: A systematic review of MEDLINE and Web of Science included studies reporting outcomes (prenatal and postnatal torsion, spontaneous resolution and surgery) of fetuses with ovarian cysts. Subgroup analysis was performed according to cyst diameter at diagnosis and cysts ≥40 mm. RESULTS: Ninety-two non-randomised studies reported on 380 cysts (324 observed and 56 aspirated in utero) in 365 fetuses. All studies were case reports or series with high heterogeneity and risk of bias. The overall spontaneous resolution rate of conservatively managed cysts was 46%, yet decreased with increasing cyst size. Risk of prenatal ovarian torsion in conservatively managed cases depended on cyst size and was particularly important in the range 30 to 59 mm (15–34%). The rate of prenatal torsion in simple cysts ≥40 mm was lower in aspirated than conservatively managed cysts (0% vs 10%, p = 0.03). Aspirated cysts had lower rates of postnatal surgery (7%) compared with conservatively managed cysts (49%, p < 0.001). CONCLUSION: Cysts 30 to 59 mm were at highest risk of torsion. Simple cysts >40 mm had lower rates of torsion when aspirated prenatally. Randomised studies and safety data are needed prior to routine prenatal ovarian cyst aspiration

Liver secretin receptor predicts portoenterostomy outcomes and liver injury in biliary atresia

Biliary atresia (BA) is a chronic neonatal cholangiopathy characterized by fibroinflammatory bile duct damage. Reliable biomarkers for predicting native liver survival (NLS) following portoenterostomy (PE) surgery are lacking. Herein we explore the utility of 22 preidentified profibrotic molecules closely connected to ductular reaction (DR) and prevailing after successful PE (SPE), in predicting PE outcomes and liver injury. We used qPCR and immunohistochemistry in a BA cohort including liver samples obtained at PE (n = 53) and during postoperative follow-up after SPE (n = 25). Of the 13 genes over-expressed in relation to cholestatic age-matched controls at PE, only secretin receptor (SCTR) expression predicted cumulative 5-year NLS and clearance of jaundice. Patients in the highest SCTR expression tertile showed 34–55% lower NLS than other groups at 1–5 years after PE (P = 0.006–0.04 for each year). SCTR expression was also significantly lower [42 (24–63) vs 75 (39–107) fold, P = 0.015] among those who normalized their serum bilirubin after PE. Liver SCTR expression localized in cholangiocytes and correlated positively with liver fibrosis, DR, and transcriptional markers of fibrosis (ACTA2) and cholangiocytes (KRT7, KRT19) both at PE and after SPE. SCTR is a promising prognostic marker for PE outcomes and associates with liver injury in BA

Preservation of micro-architecture and angiogenic potential in a pulmonary acellular matrix obtained using intermittent intra-tracheal flow of detergent enzymatic treatment

Tissue engineering of autologous lung tissue aims to become a therapeutic alternative to transplantation. Efforts published so far in creating scaffolds have used harsh decellularization techniques that damage the extracellular matrix (ECM), deplete its components and take up to 5 weeks to perform. The aim of this study was to create a lung natural acellular scaffold using a method that will reduce the time of production and better preserve scaffold architecture and ECM components. Decellularization of rat lungs via the intratracheal route removed most of the nuclear material when compared to the other entry points. An intermittent inflation approach that mimics lung respiration yielded an acellular scaffold in a shorter time with an improved preservation of pulmonary micro-architecture. Electron microscopy demonstrated the maintenance of an intact alveolar network, with no evidence of collapse or tearing. Pulsatile dye injection via the vasculature indicated an intact capillary network in the scaffold. Morphometry analysis demonstrated a significant increase in alveolar fractional volume, with alveolar size analysis confirming that alveolar dimensions were maintained. Biomechanical testing of the scaffolds indicated an increase in resistance and elastance when compared to fresh lungs. Staining and quantification for ECM components showed a presence of collagen, elastin, GAG and laminin. The intratracheal intermittent decellularization methodology could be translated to sheep lungs, demonstrating a preservation of ECM components, alveolar and vascular architecture. Decellularization treatment and methodology preserves lung architecture and ECM whilst reducing the production time to 3 h. Cell seeding and in vivo experiments are necessary to proceed towards clinical translation

New techniques in the analysis of geophysical data modelled as a multichannel autoregressive random process

Geophysical measurements can often be described in terms of multichannel, autoregressive data models from which one can directly derive measures of the harmonic composition of the underlying geophysical process and its inherent self-predictability.We explore methods for and uses of multichannel autoregressive data modelling in a geophysical context.Autoregressive data modelling using the least-squares linear prediction method is generalized to multichannel time series. A recursive algorithm is obtained for the formation of the system of multichannel normal equations which determine the least-squares solution of the multichannel linear prediction problem. Solution of these multichannel normal equations is accomplished by the Cholesky factorization method.The corresponding multichannel Maximum Entropy spectra derived from these least-squares estimates of the autoregressive model parameters are compared to that obtained using those parameters estimated by a multichannel generalization of Burg's algorithm. Numerical experiments have shown that the multichannel spectra obtained using the least-squares method provides for more accurate frequency determination for truncated sinusoids in the presence of additive white noise

Monte Carlo studies of the square Ising model with next-nearest-neighbor interactions

We apply a new entropic scheme to study the critical behavior of the square-lattice Ising model with nearest- and next-nearest-neighbor antiferromagnetic interactions. Estimates of the present scheme are compared with those of the Metropolis algorithm. We consider interactions in the range where superantiferromagnetic (SAF) order appears at low temperatures. A recent prediction of a first-order transition along a certain range (0.5-1.2) of the interaction ratio (R=Jnnn/Jnn) is examined by generating accurate data for large lattices at a particular value of the ratio (R=1). Our study does not support a first-order transition and a convincing finite-size scaling analysis of the model is presented, yielding accurate estimates for all critical exponents for R=1. The magnetic exponents are found to obey &quot;weak universality&quot; in accordance with a previous conjecture

Congenital vascular anomalies of the liver

Congenital vascular anomalies of the liver include a range of malformations of the portal venous, hepatic arterial and venous systems. Congenital portosystemic shunts and arteriovenous malformations make up the two most frequent such malformations. While infantile haemangiomas of the liver, endothelial tumours characterised by vascular proliferation should also be considered, as a proportion of them form prenatally. Evidence to support treatment strategies for these infants and children has been mainly based on small case series. In this review, we explore classification, clinical presentation, investigation and treatment strategie

Oesophageal atresia with no distal tracheoesophageal fistula: Management and outcomes from a population-based cohort.

Purpose To describe the incidence and outcomes to one-year in infants born with oesophageal atresia (OA) with no distal tracheoesophageal fistula within a population cohort. Method A prospective multicentre population cohort study was undertaken of all infants born with OA investigating clinical outcomes up to one year following initial surgery. Outcomes of infants with OA and a lower pouch fistula have previously been reported. A subgroup analysis describing the outcomes of infants with OA and no tracheoesophageal fistula, (Type A) and those with only an upper pouch fistula, (Type B) was performed. Main Results Twenty-one of 151 infants were diagnosed with Type A or B oesophageal atresia (14%). Fifteen were Type A (71%) and 6 Type B (29%). With the exception of an infant with Type A, who died before reconstruction; all but four infants (all Type B) underwent more than one operation. Median time to delayed primary anastomosis in infants with Type A and Type B was 82 days (75-89 days) (n=7). The median time to oesophageal replacement was 94 days (89-147 days) (n=8). Median length of stay for infants with Type A or B OA from first operation to first discharge was 101 days (31-123 days). Conclusions Oesophageal atresia with no distal tracheoesophageal fistula is uncommon. Infants with</p