Critical Binder cumulant in two-dimensional anisotropic Ising models

The Binder cumulant at the phase transition of Ising models on square lattices with various ferromagnetic nearest and next-nearest neighbour couplings is determined using mainly Monte Carlo techniques. We discuss the possibility to relate the value of the critical cumulant in the isotropic, nearest neighbour and in the anisotropic cases to each other by means of a scale transformation in rectangular geometry, to pinpoint universal and nonuniversal features.Comment: 7 pages, 4 figures, submitted to J. Phys.

The Efficiency of U.S. Public Space Utilization During the COVID-19 Pandemic

The COVID-19 pandemic has called for and generated massive novel government regulations to increase social distancing for the purpose of reducing disease transmission. A number of studies have attempted to guide and measure the effectiveness of these policies, but there has been less focus on the overall efficiency of these policies. Efficient social distancing requires implementing stricter restrictions during periods of high viral prevalence and rationing social contact to disproportionately preserve gatherings that produce a good ratio of benefits to transmission risk. To evaluate whether U.S. social distancing policy actually produced an efficient social distancing regime, we tracked consumer preferences for, visits to, and crowding in public locations of 26 different types. We show that the United States’ rationing of public spaces, postspring 2020, has failed to achieve efficiency along either dimension. In April 2020, the United States did achieve notable decreases in visits to public spaces and focused these reductions at locations that offer poor benefit-to-risk tradeoffs. However, this achievement was marred by an increase, from March to April, in crowding at remaining locations due to fewer locations remaining open. In December 2020, at the height of the pandemic so far, crowding in and total visits to locations were higher than in February, before the U.S. pandemic, and these increases were concentrated in locations with the worst value-to-risk tradeoff

Prediction of stillbirth from maternal demographic and pregnancy characteristics

Objectives: To develop a model for prediction of stillbirth based on maternal characteristics and components of medical history and evaluate the performance of screening of this model for all stillbirths and those due to impaired placentation and unexplained causes. Methods: This was a prospective screening study of 113,415 singleton pregnancies at 11+0-13+6 and 19+0-24+6 weeks’ gestation. The population included 113,019 live births and 396 (0.35%) antepartum stillbirths; 230 (58%) were secondary to impaired placentation and 166 (42%) were due to other or unexplained causes. Multivariate logistic regression analysis was used to determine the factors from maternal characteristics and medical history which provided a significant contribution to the prediction of stillbirth. Results: The risk for stillbirth increased with maternal weight (OR 1.01 per kg after 69 kg), was higher in women of Afro-Caribbean race (OR 2.01), assisted conception (OR 1.79), cigarette smokers (OR 1.71), those with a history of chronic hypertension (OR 2.62), SLE/APS (OR 3.61) or diabetes mellitus (OR 2.55) and was increased in parous women with a history of previous stillbirth (OR 4.81). The model predicted 26% of unexplained stillbirths and 31% of those due to impaired placentation at FPR of 10%; within the impaired placentation group the DR of stillbirth at 37 weeks (38% vs 28%). Conclusions: A model based on maternal characteristics and medical history recorded in early pregnancy can potentially predict one third of subsequent stillbirths. The extent to which such stillbirths could be prevented remains to be determined

Uterine artery pulsatility index at 30-34 weeks' gestation in the prediction of adverse perinatal outcome

Objective: To investigate the potential value of uterine artery Doppler at 30 34 weeks’ gestation in the prediction of adverse perinatal outcome. Methods: Screening study in 30,780 singleton pregnancies at 30 34 weeks. Uterine artery pulsatility index (PI) was measured and the values were converted to multiples of the median (MoM) after adjustment from variables in maternal characteristics and medical history that affect the measurements. Multivariable logistic regression analysis was used to determine if uterine artery PI had a significant additional contribution to maternal characteristics, medical history and obstetric factors in predicting adverse outcome. The detection rate (DR) and false positive rate (FPR) of screening by uterine artery PI were estimated for stillbirth, cesarean section for fetal distress, umbilical arter ial cord blood pH <7.0 or umbilical venous pH <7.1 and Apgar score <7 at 5 minutes. Results: The incidence of adverse perinatal outcome was higher in small for gestational age (SGA) than in non SGA fetuses, but the majority of cases for each adverse outcome were in the non SGA group, including about 70% of stillbirths and more than 80% of cases of cesarean section for fetal distress, low cord blood pH and low Apgar score. The performance of uterine artery PI >95 th percentile in screening for each adverse outcome was poor with DR of 6 16% and FPR of 5 6%. T he DR of high uterine artery PI for adverse outcome was higher in the SGA than non SGA groups, including 24% vs. 13% for stillbirth , 15% vs. 5% for cesarean section for fetal distress, 22% vs. 9% for low cord blood pH and 20% vs. 3% for low Apgar score. Conclusion: High uterine artery PI at 30 34 weeks’ gestation may be useful in the prediction of adverse perinatal outcome in pregnancies with SGA fetuses, but not in those with non SGA fetuses

Critical Binder cumulant for isotropic Ising models on square and triangular lattices

Using Monte Carlo techniques, the critical Binder cumulant U* of isotropic nearest-neighbour Ising models on square and triangular lattices is studied. For rectangular shapes, employing periodic boundary conditions, U* is found to show the same dependence on the aspect ratio for both lattice types. Similarly, applying free boundary conditions for systems with square as well as circular shapes for both lattices, the simulational findings are also consistent with the suggestion that, for isotropic Ising models with short-range interactions, U* depends on the shape and the boundary condition, but not on the lattice structure.Comment: 7 pages, 4 figures, submitted to J. Stat. Mec

Effect of Intermittent Pneumatic Foot Compression on Popliteal Artery Haemodynamics

AbstractPurpose: the aim was to investigate the effect of intermittent pneumatic foot compression (IPCfoot) on popliteal artery haemodynamics in normal individuals and in patients with intermittent claudication due to peripheral vascular disease (PVD) (Fontaine stage II). Material and methods: popliteal artery volume flow [vFl], pulsatility index [PI], mean velocity [mV], peak systolic [PSV] and end diastolic velocity [EDV], in 25 limbs of 20 normal subjects and 40 limbs of 32 stable claudicants were obtained in the sitting position before, during and within 30 seconds after the application of IPCfoot(applied pressure: 120 mmHg; inflation time: 3 seconds; deflation time: 17 seconds) using colour-flow duplex imaging (CFDI). The reproducibility of flow velocity estimations using CFDI in the horizontal [hor] (recovery) and sitting [sit] positions was evaluated in 20 limbs of normal controls and 20 limbs of claudicants. Results: popliteal artery vFl, mV, PSV and PI measurements were performed with a coefficient of variation (CV) of less than 14.6% among claudicants and of less than 13.3% in normal subjects. EDV is the least reproducible parameter with an overall CV range of 10.2–21.5% in normal controls and 9.1–18.6% in arteriopaths. On application of IPCfootpopliteal artery vFl increased by 111% in the control group (p<0.001) and by 51% in the claudicants (p<0.001). Within 30 seconds of the cessation of pump action flow decreased significantly in both groups (p<0.001), but maintained a significantly higher level than that at baseline (p<0.001, in both groups). The mV, PSV and EDV showed a similar pattern of significant changes. Both in normals and claudicants, the PI decreased with IPCfoot(p<0.001) and increased post-compression; however, it was significantly lower than baseline (p<0.005) within 30 seconds of impulse delivery. Conclusions: current CFDI technology enables a reproducible estimation of popliteal artery flow velocities. IPCfootcan significantly augment arterial calf inflow on an acute basis both in normals and claudicants. The increase of EDV and decrease of PI indicate that attenuation of peripheral resistance to flow is the main mechanism underlying the popliteal artery vFl enhancement on application of IPCfoot. Prospective trials on the long-term effect of IPCfootin the management of patients with PVD are indicated from the results of this study

Endoscopic placental laser coagulation in dichorionic and monochorionic triplet pregnancies

Objective: To report outcome of monochorionic (MC) and dichorionic (DC) triamniotic (TA) triplet pregnancies treated with endoscopic laser coagulation of communicating placental vessels for severe fetofetal transfusion syndrome (FFTS) and selective fetal growth restriction (sFGR). Methods: Laser surgery was performed at 18 (15-24) weeks gestation in 11 MCTA and 33 DCTA pregnancies complicated by FFTS and 14 DCTA pregnancies complicated by sFGR. Data from our study and previous reports were pooled using meta-analytic techniques. Results: Survival of at least one baby and survival among all fetuses was 97.0% and 72.7% in DCTA pregnancies with FFTS, 78.6% and 52.4% in DCTA pregnancies with sFGR and 81.8% and 39.4% in MCTA pregnancies with FFTS. In the combined data from our study and previous reports, the pooled survival rates in 132 DCTA pregnancies with FFTS were 94.4% and 76.1% and in 29 MCTA pregnancies with FFTS were 80.6% and 57.5%. Conclusions: Survival after laser surgery is higher in DC triplets with FFTS than those with sFGR and in DC than MC triplets with FFTS

Lipid Composition of Comedones Compared With That of Human Skin Surface in Acne Patients

TLC† analysis of comedo lipids from the face, neck, chest and back of acne patients of both sexes, ages 12 to 26 years, (some 65 specimens) gave the same gross composition except for hydrocarbons more saturated than squalene and lipids more polar than free cholesterol. Quantitative data (chromatography plus GLC of isolated fractions) on both comedo and surface lipids from each of 3 acne patients revealed the following. Free fatty acids plus triglycerides comprised ∼63% of both comedo and skin surface lipids. However, for the comedo, 90% of this sum was free fatty acids compared with only 25% for surface lipid. This implies that triglycerides in comedo lipids are nearly completely hydrolyzed but only 25% hydrolyzed in surface lipids. GLC patterns of the free fatty acids were almost identical for both surface and comedo lipids in all 3 subjects except for slightly more unsaturated acids in surface lipids. For comedo and surface lipids respectively, wax esters were 14% and 24%, sterol esters 4% and 2%, free cholesterol 12% and 2%, and squalene 8% and 9%. Absence of free alcohols and constancy of GLC composition of the entire wax ester fraction indicated it was not hydrolyzed in either surface or comedo lipids. GLC composition of the entire sterol ester fraction from comedones indicated that the fatty acids were derived from epidermis and sebum