Proton Compton Scattering from Linearly Polarized Gamma Rays.

Differential cross sections for Compton scattering from the proton have been measured at scattering angles of 55°, 90°, and 125° in the laboratory frame using quasimonoenergetic linearly (circularly) polarized photon beams with a weighted mean energy value of 83.4 MeV (81.3 MeV). These measurements were performed at the High Intensity Gamma-Ray Source facility at the Triangle Universities Nuclear Laboratory. The results are compared to previous measurements and are interpreted in the chiral effective field theory framework to extract the electromagnetic dipole polarizabilities of the proton, which gives α_{E1}^{p}=13.8±1.2_{stat}±0.1_{BSR}±0.3_{theo},ß_{M1}^{p}=0.2∓1.2_{stat}±0.1_{BSR}∓0.3_{theo} in units of 10^{-4} fm^{3}.

The basic reproduction number and prediction of the epidemic size of the novel coronavirus (COVID-19) in Shahroud, Iran.

The aim of this study was to estimate the basic reproduction number (R0) of COVID-19 in the early stage of the epidemic and predict the expected number of new cases in Shahroud in Northeastern Iran. The R0 of COVID-19 was estimated using the serial interval distribution and the number of incidence cases. The 30-day probable incidence and cumulative incidence were predicted using the assumption that daily incidence follows a Poisson distribution determined by daily infectiousness. Data analysis was done using 'earlyR' and 'projections' packages in R software. The maximum-likelihood value of R0 was 2.7 (95% confidence interval (CI): 2.1-3.4) for the COVID-19 epidemic in the early 14 days and decreased to 1.13 (95% CI 1.03-1.25) by the end of day 42. The expected average number of new cases in Shahroud was 9.0 ± 3.8 cases/day, which means an estimated total of 271 (95% CI: 178-383) new cases for the period between 02 April to 03 May 2020. By day 67 (27 April), the effective reproduction number (Rt), which had a descending trend and was around 1, reduced to 0.70. Based on the Rt for the last 21 days (days 46-67 of the epidemic), the prediction for 27 April to 26 May is a mean daily cases of 2.9 ± 2.0 with 87 (48-136) new cases. In order to maintain R below 1, we strongly recommend enforcing and continuing the current preventive measures, restricting travel and providing screening tests for a larger proportion of the population.

Vitamin D deficiency and diabetic retinopathy risk.

PURPOSE: Vitamin D deficiency may play an important role in the development and progression of diabetic retinopathy. The present study aimed to assess the relationship between vitamin D deficiency and the likelihood of diabetic retinopathy. METHODS: This nested case-control study was conducted on all type II diabetic patients among the participants of the third phase of the Shahroud eye cohort study. Overall, 278 patients aged 50 to 74 years, 101 in the case group (diabetic retinopathy) and 178 in the control group (diabetic without retinopathy), were assessed. Serum levels of vitamin D on admission were measured for all participants by a radio immunoassay (RIA) technique. RESULTS: The overall prevalence of vitamin D deficiency (defined as a vitamin D level of less than or equal to 20mg/dL) was 30.7%. Comparison of the serum level of vitamin D across the three groups - without retinopathy, with non-proliferative retinopathy, and with proliferative retinopathy - showed a significantly lower level of this marker in the latter group (P=0.036). Reducing vitamin D to less than or equal to 20ng/mL increased the odds of proliferative retinopathy by 6.25 times (P value: 0.027). CONCLUSION: Vitamin D deficiency is a potential risk factor for diabetes-related proliferative retinopathy.

Development of a variable-energy, high-intensity, pulsed-mode ion source for low-energy nuclear astrophysics studies.

The primary challenge in directly measuring nuclear reaction rates near stellar energies is their small cross sections. The signal-to-background ratio in these complex experiments can be significantly improved by employing high-current (mA-range) beams and novel detection techniques. Therefore, the electron cyclotron resonance ion source at the Laboratory for Experimental Nuclear Astrophysics underwent a complete upgrade of its acceleration column and microwave system to obtain high-intensity, pulsed proton beams. The new column uses a compression design with O-ring seals for vacuum integrity. Its voltage gradient between electrode sections is produced by the parallel resistance of channels of chilled, deionized water. It also incorporates alternating, transverse magnetic fields for electron suppression and an axially adjustable beam extraction system. Following this upgrade, the operational bremsstrahlung radiation levels and high-voltage stability of the source were vastly improved, over 3.5 mA of target beam current was achieved, and an order-of-magnitude increase in normalized brightness was measured. Beam optics calculations, structural design, and further performance results for this source are presented.

Increased concentrations of arachidonic acid lipoxygenase metabolites in amniotic fluid during parturition.

This study was undertaken to examine whether spontaneous labor at term is associated with changes in the amniotic fluid concentrations of arachidonate lipoxygenase metabolites. Amniotic fluid was obtained from 15 women at term in active labor (with cervical dilatation of at least 6 cm) and from 15 nonlaboring control women matched for maternal age, parity, and gestational age. Cultures of amniotic fluid for bacteria and mycoplasma were negative. Products of arachidonate lipoxygenase metabolism--12-hydroxyeicosatetraenoic acid (12-HETE), 15-hydroxyeicosatetraenoic acid (15-HETE), and leukotriene B4--were measured by radioimmunoassay. The median concentrations of 12-HETE, 15-HETE, and leukotriene B4 in the amniotic fluid of nonlaboring women were 11.50 ng/mL, 0.45 ng/mL, and 21 pg/mL, respectively, and in the amniotic fluid of laboring women, 24.63 ng/mL, 4.34 ng/mL, and 96 pg/mL, respectively. The differences between labor and nonlabor amniotic fluid concentrations of all three lipoxygenase products were significant (P less than .05, Wilcoxon test). These observations are consistent with involvement of products of the lipoxygenase pathway of arachidonic acid metabolism in the mechanism of human parturition.

The clinical value of gas-liquid chromatography in the detection of intra-amniotic microbial invasion.

Short-chain organic acids are byproducts of bacterial metabolism, and their detection by gas-liquid chromatography (GLC) in amniotic fluid has been proposed as a rapid, sensitive, and specific method for the diagnosis of infection. This study was conducted to determine whether GLC analysis of amniotic fluid would be helpful in a population of women in whom the Gram stain examination was negative. Amniotic fluid was retrieved by transabdominal amniocentesis from three groups of patients. Group 1 (negative control) contained 14 women with term pregnancies without clinical and microbiologic evidence of infection of the amniotic cavity; group 2 (positive control) included 17 women with a positive Gram stain examination and culture of amniotic fluid; group 3 (study group) comprised 25 women at risk for intra-amniotic infection who had a negative Gram stain of amniotic fluid. None of the patients in group 1 and 16 of 17 patients (94.1%) in group 2 had pathologic short-chain organic acids in the amniotic fluid. Seven of the 25 patients in group 3 had a positive amniotic fluid culture and only two had an abnormal GLC pattern. Of the remaining 18 patients with negative amniotic fluid cultures, eight had abnormal GLC results. In group 3, the sensitivity of GLC was 28.5% and the specificity was 55.5%. Gas-liquid chromatographic analysis of amniotic fluid has limited clinical value in the prediction of amniotic fluid culture when the Gram stain examination is negative.

Visual impairment in the 40- to 64-year-old population of Shahroud, Iran.

PURPOSE: To determine the prevalence of visual impairment by age and gender in Shahroud. METHODS: Using random cluster sampling, 6311 Shahroud inhabitants who were between 40 and 64 years old were invited for ophthalmological examinations. Visual acuity worse than 0.5 LogMAR (20/60) and 1.3 LogMAR (20/400) in the better eye was regarded as low vision and blindness, respectively. The cause of blindness was determined by an ophthalmologist and in a person with more than one cause, the most correctable cause was regarded as the main cause. RESULTS: This study was conducted on 5190 participants (response rate: 82.2%). On the basis of presenting visual acuity, the prevalence of low vision and blindness was found to be 1.8% (95% confidence interval (CI): 1.4-2.10) and 0.5% (95% CI: 0.3-0.7), respectively. Based on corrected vision, these values were 0.5% (95% CI: 0.3-0.7) and 0.3% (95% CI: 0.1-0.4), respectively. Visual impairment increased with age in women (P<0.001). Uncorrected refractive errors (63.9%), cataract (20.2%), and amblyopia (5.9%) were the most common causes of visual impairment based on presenting vision. Based on corrected vision, however, cataract (42.5%), amblyopia (12.5%), and retinitis pigmentosa (7.5%) were the most common causes of visual impairment. CONCLUSION: Although the prevalence of visual impairment in the city of Shahroud was determined to be lower than two previous studies in the country, correction of refractive errors and cataract could minimize the rate of visual impairment in this population as they were shown to comprise 85% of the causes of visual impairment. The elderly women need to receive more attention.

Prostaglandin concentrations in amniotic fluid of women with intra-amniotic infection and preterm labor.

This study was undertaken to examine the effects of intrauterine infection and preterm labor on the amniotic fluid concentrations of prostaglandins in women with premature rupture of the membranes. Amniotic fluid was obtained from four groups of patients with premature rupture of the membranes: group 1, patients without labor or infection; group 2, patients with labor but without infection; group 3, patients with an intra-amniotic infection but without labor; group 4, patients with both infection and labor. Prostaglandins E2 and F2a were measured by radioimmunoassays. Preterm labor, in the absence of infection, was not associated with significant increases in amniotic fluid concentrations of prostaglandins. Women with preterm labor and intra-amniotic infections had higher amniotic fluid concentrations of prostaglandins than women with preterm labor in the absence of infection or women with intra-amniotic infection in the absence of labor. These observations are compatible with the participation of prostaglandins in the mechanisms of onset of preterm labor associated with intra-amniotic infection.

The value of the leukocyte esterase test in diagnosing intra-amniotic infection.

This communication examines the diagnostic value of the leukocyte esterase activity (LEA) test in the detection of intra-amniotic infection. Amniotic fluid from 171 consecutive patients with premature rupture of membranes (n = 149) and preterm labor (n = 22) was obtained through amniocentesis. Gram stain, bacterial and mycoplasma cultures, and LEA tests were performed. The LEA had a sensitivity of 19%, a specificity of 86.7%, a positive predictive value (PPV) of 42.3% and a negative predictive value (NPV) of 67.6% in the prediction of a positive amniotic fluid culture (prevalence of positive cultures = 33.9%). The Gram stain had a sensitivity of 36.2%, specificity of 94.7%, PPV of 77.8%, and NPV of 74.3%. When both tests were combined, a significant increase in sensitivity to 50% was observed. This was associated with a drop in specificity to 81.4%. There was a correlation between the number of white blood cells in the amniotic fluid and the result of the LEA test. A positive LEA assay was associated with an increased likelihood of postpartum endometritis, but not with clinical chorioamnionitis or neonatal infectious morbidity.

Arachidonate lipoxygenase metabolites in amniotic fluid of women with intra-amniotic infection and preterm labor.

This study was undertaken to examine the effects of intrauterine infection and preterm labor on the amniotic fluid concentrations of arachidonate lipoxygenase metabolites in women with premature rupture of membranes. Amniotic fluid was obtained from four groups of women with premature rupture of membranes: group 1, women without labor or infection; group 2, women with labor but without infection; group 3, women with intra-amniotic infection but without labor; and group 4, women with both infection and labor. 12-Hydroxyeicosatetraenoic acid, 15-hydroxyeicosatetraenoic acid, and leukotriene B4 were measured by radioimmunoassays. Amniotic fluid concentrations of 12-hydroxyeicosatetraenoic acid were found not to differ significantly among the four groups. Amniotic fluid concentrations of 15-hydroxyeicosatetraenoic acid in group 4 were significantly higher than in women in groups 1 and 3 (p less than 0.05). In addition, amniotic fluid concentrations in leukotriene B4 were significantly higher in group 4 than in any of the other three groups (p less than 0.05). Leukotriene B4 concentrations were higher in groups 2 and 3 than in group 1, suggesting that the presence of both labor and infection increases the concentration of this metabolite in amniotic fluid. Infection and labor had an additive effect in the elevation of amniotic fluid concentrations of leukotriene B4. These results suggest that the amniotic fluid concentrations of arachidonate lipoxygenase metabolites are affected differently by the presence of infection and labor in women with premature rupture of membranes.

Diagnosis of intra-amniotic infection: the acridine orange stain.

The rapid diagnosis of intra-amniotic infection in patients with premature rupture of the membranes (PROM) and preterm labor is of utmost importance. The Gram's stain examination of amniotic fluid can only detect half of these infections. The acridine orange (AO) stain has been claimed to be superior to the Gram's stain in the detection of bacteria in biologic fluids. Therefore, we undertook the present study to examine the value of AO in the detection of bacteria in amniotic fluid. One hundred and thirty-eight patients with a culture-documented prevalence of intra-amniotic infection of 23.2% were studied. The diagnostic indices of the AO were: sensitivity, 43.8%, specificity, 97.2%, positive predictive value, 82.8%, and negative predictive value, 85.1%; the diagnostic indices for the Gram's stain were: sensitivity, 46.8%, specificity, 98.1%, positive predictive value, 88.2%, and negative predictive value, 85.9%. There was no difference in the diagnostic values of the tests. The agreement between the two techniques was substantial, as indicated by a kappa index of 0.72 (SE = 0.17, p less than 0.001). The AO offered no significant advantage over the Gram's stain examination of amniotic fluid in the detection of intra-amniotic infection. However, the AO stain was able to identify mycoplasma infections that escaped detection by the Gram's stain. Therefore, the AO is presently the only microscopic technique capable of detecting mycoplasma in amniotic fluid.

The value and limitations of the Gram stain examination in the diagnosis of intraamniotic infection.

Gram stain examination of amniotic fluid is a method used for the rapid diagnosis of intraamniotic infection in patients with preterm premature rupture of membranes and preterm labor. The management of these patients relies heavily on the Gram stain results. Therefore, it is critical that the diagnostic value and limitations, optimal technique, and outcome correlates be precisely established. Most studies have focused on culture results rather than on Gram stain results to describe neonatal and maternal outcome. However, management is based on the Gram stain because culture results are not immediately available. One hundred eighty-seven amniocenteses were performed in 131 patients with preterm premature rupture of the membranes (n = 90) and preterm labor (n = 41). Spun and unspun Gram stains were performed. Centrifugation of the sample did not improve the sensitivity of the technique significantly. The agreement between the two methods was substantial (kappa index 0.89, p less than 0.001). The sensitivity of the Gram stain was 44.8% and the specificity was 97.6%. The sensitivity of the Gram stain was directly proportional to the number of bacteria present in amniotic fluid. In the presence of greater than 10(5) colony forming units per milliliter, 80% of the Gram stains were positive. The absence of both bacteria and white blood cells in a smear was associated with a negative culture of amniotic fluid in 95% of the cases. Clinical chorioamnionitis was associated with a positive Gram stain of amniotic fluid (p less than 0.001). There was a trend toward a higher incidence of endometritis in patients with a positive Gram stain compared with those with a negative Gram stain (p = 0.07). There was no neonatal infectious morbidity in patients with a true negative Gram stain. Patients with a false negative Gram stain had a 25% incidence of neonatal infectious complications (proved and suspected sepsis).

Clinical significance, prevalence, and natural history of thrombocytopenia in pregnancy-induced hypertension.

The purpose of this study was to establish the prevalence and clinical significance of thrombocytopenia in pregnancy-induced hypertension (PIH). Thrombocytopenia, defined as a platelet count less than 100,000/mm3 was found in 11.6% of all patients with PIH. Logistic regression analysis was used to assess the relative contribution of thrombocytopenia, proteinuria, and the degree of hypertension to maternal and perinatal outcome. Thrombocytopenia was the principal contributor to the occurrence of abdominal pain, liver dysfunction, the presence of schistocytes in the peripheral smear, proteinuria, fetal distress, and the requirement for blood transfusions. Thrombocytopenia was also associated with a higher incidence of preterm delivery and intrauterine growth retardation. The nadir platelet count occurred within 48 hours of delivery in 56.7% (21 of 37) of cases. The median number of days for recovery of the thrombocytopenia was 2.0 days (range, 0 to 8 days). In five patients thrombocytopenia preceded the clinical manifestations of PIH. We conclude that thrombocytopenia is an independent and important risk factor for the occurrence of maternal and perinatal complications in PIH.

Clinical significance of liver dysfunction in pregnancy-induced hypertension.

Hepatic dysfunction is one of the frequent manifestations of multisystemic involvement in preeclampsia. This study was conducted to establish the impact of liver dysfunction on maternal and neonatal outcome in women with pregnancy-induced hypertension (PIH). The prevalence of liver dysfunction as determined by an elevated serum glutamic oxalacetic transaminase (SGOT) concentration was 21% in a population of 355 patients with PIH. Liver dysfunction was associated with the presence of severe hypertension, proteinuria, a lower platelet count, and renal compromise (elevated blood urea nitrogen, creatinine, and uric acid serum concentrations). Abdominal pain was also associated with an SGOT elevation. Liver dysfunction was associated with intrauterine growth retardation and prematurity. Furthermore, the association with these neonatal complications was independent from the severity of the hypertension and the presence of proteinuria. Thus, we conclude that liver dysfunction is a frequent complication of PIH and that it is an independent risk factor for maternal and perinatal complications.

Labor and infection. II. Bacterial endotoxin in amniotic fluid and its relationship to the onset of preterm labor.

We have previously reported the detection of endotoxin in the amniotic fluid of patients with gram-negative intraamniotic infection. Endotoxin or lipopolysaccharide is a potent biologic product capable of inducing prostaglandin release from several cell types and, therefore, may be involved in the onset of human parturition in the presence of intraamniotic infection. This article describes a technique for the quantification of endotoxin in amniotic fluid. The method uses a computer-assisted quantification of the turbidimetric reaction between the Limulus amebocyte lysate and endotoxin. Serial dilutions of Escherichia coli endotoxin in culture-negative amniotic fluid were prepared, and the samples were run in the assay. Amniotic fluid was found to enhance the reaction, and a dilution of 1:20 was required for this biologic fluid to behave similarly to pyrogen-free water. The sensitivity of this kinetic turbidimetric technique in the detection of endotoxin in amniotic fluid was 40 pg/ml. This method was applied to the quantification of endotoxin concentration in amniotic fluid in 26 patients with intraamniotic infection and premature rupture of membranes. Patients in active labor had higher concentrations of endotoxin (median = 47,514 pg/ml) than nonlaboring patients (median = 635 pg/ml) (p less than 0.025). Therefore, women with preterm labor had a higher median concentration of endotoxin in amniotic fluid than patients who were not in labor.